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IVIAIMLJAL 



Serial Number / £ C C: 



TYPE 191 



CONSTANT 

AMPLITUDE 

SIGNAL 

GENERATOR 



Tektronix, Inc. 

S.W. Millikan Way • P. O. Box 500 • Beaverton, Oregon 97005 • Phone 644-0161 • Cables: Tektronix 





WARRANTY 

All Tektronix instruments are warranted 
against defective materials and workman 
ship for one year. Tektronix transformers, 
manufactured in our own plant, are war- 
ranted for the life of the instrument. 

Any questions with respect to the war- 
ranty mentioned above should be taken 
up with your Tektronix Field Engineer. 

Tektronix repair and replacement-part 
service is geared directly to the field, 
therefore all requests for repairs and re- 
placement parts should be directed to the 
Tektronix Field Office or representative in 
your area. This procedure will assure you 
the fastest possible service. Please include 
the instrument Type and Serial or Model 
Number with all requests for parts or 
service. 

Specifications and price change privi- 
leges reserved. 

Copyright @ 1966 by Tektronix, Inc., 
Beaverton, Oregon. Printed in the United 
States of America. All rights reserved. 
Contents of this publication may not be 
reproduced in any form without permission 
of the copyright owner. 






CONTENTS 



Section 1 
Section 2 
Section 3 
Section 4 
Section 5 
Section 6 

Section 7 

Section 8 
Section 9 



Characteristics 
Operating Instructions 
Circuit Description 
Maintenance 
Performance Check 
Calibration 

Parts Ordering Information 
Abbreviations and Symbols 

Electrical Parts List 
Mechanical Parts List Information 
Mechanical Parts List 

Diagrams 

Mechanical Parts List Illustrations 



Accessories 

Abbreviations and symbols used in this manual 
are based on, or taken directly from, IEEE 
Standard 260 “Standard Symbols for Units", 
MIL-STD-12B and other standards of the elec- 
tronics industry. Change information, if any, 
is located at the rear of this manual. 





Fig. 1*1. Type 191 Constant Amplitude Signal Generator. 



Type 191 



SECTION I 
CHARACTERISTICS 



General 

The Tektronix Type 191 Constant-Amplitude Signal 
Generator produces sine waves whose amplitude remains 
constant as the frequency is varied, provided the load limita- 
tions of the instrument are not exceeded. Front-panel con- 
trols indicate the peak-to-peak voltage of these sine waves 
at the input to a 50 ohm load. 

This instrument is useful for making frequency-response 
measurements of broadband devices operating in the fre- 
quency range from 350 kilohertz to 100 megahertz. 

The following characteristics apply over an ambient temp- 
erature range of 0° C to +50° C. Warm-up time for the 
given accuracies is 5 minutes at 25° C ±5° C. 



MECHANICAL CHARACTERISTICS 



Characteristic 


Information 


Construction 


Aluminum-alloy chassis, 
panel and cabinet. 
Glass laminated 
circuit boards. 


Finish 


Anodized panel, blue 
vinyl-coated cabinet. 


Overall Dimensions 


6% inches high, 9 inches 


(measured at maximum 
points) 


wide, 1 5 5 /s inches long. 



STANDARD ACCESSORIES 

Standard accessories supplied with this instrument will be 
found on the last pullout page at the rear of this manual. 
For optional accessories, see the Tektronix, Inc. catalog. 



TYPE 191 OUTPUT 



Characteristic 


Performance Requirement 


Supplemental Information 


Frequency Accuracy 


Within ±2% of the selected frequency when 
the output is terminated with 50 ohms. When 
the output is not terminated with 50 ohms the 
accuracy is still ±2% except on the 0.5-5 V 
range where the accuracy is ±5%. 


The frequency accuracy of the 50 kHz 
reference frequency is 50 kHz ±2%. The 
tolerance takes into account the effect that 
the Frequency (dial) setting will have on 
the frequency accuracy. 


Amplitude Accuracy at 50 kHz 
into a 50 ohm ±1% load 


The 0.5-5V range is within ±3% of the 
indicated amplitude, the 50-500 mV range is 
within ±4% of the indicated amplitude, and 
the 5-50 mV range is within ±5% of the 
indicated amplitude. 


The open circuit unterminated output will 
be twice the amplitude of the terminated 
output (marked on the front panel), but 
the output tolerances will remain the same 
as those stated for the terminated output. 


Harmonic Content 




Typically less than 5%. 


Amplitude Regulation into 50 
ohms at OUTPUT connector, or 
through 5 ns (40 inches) or less 
of RG-8A/U coaxial cable. 


When a Type 191, properly terminated in 
50 ohms, is set for any output amplitude 
between 5 mV and 5.5 V, the amplitude at 
any frequency will vary less than ±3% from 
the actual amplitude value at 50 kHz, except 
for an output between 5 mV and 55 mV and 
a frequency between 42 MHz and 100 MHz 
where the amplitude variation will be less 
than +3% and —5%. 


The use of RG-8A/U coaxial cable is 
important for good amplitude regulation 
at high frequencies. A 40 inch length of 
RG-58A/U coaxial cable, for example, can 
introduce a 1.5% amplitude loss at 100 
MHz. 



POWER REQUIREMENTS 



Line Voltage Regulation 


Power supplies must regulate when the line 
Voltage is within ±10% of the appropriate 
transformer center value. 




Line Voltage Center 
Values 


105 VAC, 115 VAC, 125 VAC, 210 VAC, 230 
VAC, and 250 VAC. 


Center values obtained by using appro- 
priate transformer taps. 


Line Voltage Fuses 


Type 3AG, 0.4 amp slow-blow for 115 V 
operation. Type 3AG, 0.2 amp s!ow-blow for 
230 V operation. 




Line Frequency Operating 
Range 


50 to 400 Hz. 




Input Power Consumption 




Approximately 25 watts. 






1-1 

























SECTION 2 

OPERATING INSTRUCTIONS 



General 

To effectively use the Type 191 Constant Amplitude Signal 
Generator, the operation and capabilities of the instrument 
must be known. This section describes the operation of the 
front- and rear-panel controls and connectors, and gives 
first time operating information. 

Voltage and Fuse Considerations 

When the Type 191 is shipped from the factory, it is 
wired so it may be operated on either 115- or 230-volt 
nominal line voltages. Switching between the ranges is 
accomplished by the Line Voltage Switch (SW105) located 
on the rear-panel of the instrument. Fig. 2*1 shows the Line 
Voltage Switch (SW105) location. 

Other nominal line voltages are available by rewiring 
the Line Voltage Switch connectors to the transformer. Table 
2-1 lists the other nominal line voltages available, their 
operating ranges and the Lino Voltage Switch transformer 
connections for these line voltages. Table 2-1 alto lists the 





correct fuse size 


for each nominal s 


roltage. 








TABLE 2 


•1 




«- 


Line Voltage 
Switch 
Nominal 
Line Voltages 


Nominal 

Voltage 

Operating 

Range 


Fute 

Size 


Line Voltage 
Switch 
Transformer 
Connections 




115 


103.5 to 126 5 


0.4 A 


Factory wired to 




230 


207 to 253 


0 2 A 


terminals 2 and 
7 




105 


94 5 to 115.5 


0 4 A 


Move terminal 2 


— 


210 


189 to 231 


0.2 A 


wire to terminal 

n k. ! i 



3 and terminal 
7 wire to termi 
nal 6 



125 


1 1 25 


to 137.5 


0.4 A 


Move terminal 2 


250 


225 


to 275 


0.2 A 


wire to terminal 










1 and terminal 










7 wire to termi- 










nal 8 



Cooling Considerations 

Adequate clearance must be provided on all sides of the 
instrument to allow heat to be dissipated. The clearance 
provided by the feet at the bottom should be maintained. 
If possible, allow about two inches of clearance on the sides 
and top. Do not block or restrict the air flow holes in the 
cabinet. 

CONTROLS AND CONNECTOR 

A brief description of the function or operation of the 
front and rear panel controls and the front panel connector 
follows (see Fig. 2-1 and 2-2). 




rig. 2*1. Location of lino Voltago Switch (SW10S) on roor panol. 



Frequency Selects the desired output frequency from 

(dial) the frequency band selected by the FRE 

QUENCY RANGE switch. 

FREQUENCY Selects the desired frequency band from 

RANGE which the specific frequency can be 

obtained. 

AMPLITUDE Works in conjunction with the AMPLITUDE 
RANGE switch to determine the cali- 
brated peak to peak amplitude of the out- 
put signal, when the output is terminated 
with 50 ohms. The open circuit (untcr- 
minated] output peak to peak amplitude of 
the signal will be twice the indicated 
amplitude. 

VARIABLE Increases the output amplitude approxi- 

(AMPLITUDE) matcly up to the next fixed output ampli- 
tude of the AMPLITUDE switch, thus 
providing a continuous variation of out- 
put amplitude between the fixed ampli- 
tudes selected with the AMPLITUDE switch. 

AMPLITUDE Determines the signal amplitude (voltage) 

RANGE range from which the AMPLITUDE switch 

(PEAK TO and VARIABLE control will select the final 

PEAK INTO signal amplitude. Front-panel markings 

50 D) indicate amplitudes when the Type 191 

output is properly terminated in 50 ohms. 
If the output is not terminated, the actual 
signal output amplitudes will be two times 
the markings. 

OUTPUT Signal output coaxial connector. Output 

(R o =50 12) resistance is 50 ohms for all control settings. 



2-1 





Operating Instructions — Type 191 



Frequency Dial 




W VI 

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VvSsJ pll! 




TYPE 191 

CONSTANT AMPLITUDE 
SIGNAL GENERATOR 



AMPLITUDE 

r is 



FREQUENCY RANGE 

MioAHien 




40 

4ft 

ftO 




AMPLITUDE RANGE 

irtM *o nu -e»o wui 

ftO ftOO~V 



ft ftV 




o $ 



OUf **VT 







iti?«o4ii me eoevumo oeiocm use 



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Fig. 2-2. Type 191 front-panel. 



POWER Applies power 1o the instrument. 

Power Light Indicates that POWER switch is on and the 
instrument is connected to a line source. 



Line Voltage 
Switch 
(SW105) 



SW105 is factory wired to select either 
115* or 230-volt nominal line voltagos. The 
power transformer may be wired so that 
SW105 will select other than those line 
voltages. 



FIRST-TIME OPERATION 

The following steps will demonstrate the use of the con- 
trols and connector of the Type 191. It is recommended that 
this procedure be followed completely for familiarization 
with the instrument. 

1. Set the front- and rear-panel controls os follows: 



NOTE 

The position of the Frequency (dial) setting is 
unimportant for the 50 kHz frequency range since 
it will cause not more than a ± 1 % change in 
the output frequency. 

2. Connect the Type 191 to a power source that meets 
the voltage and frequency requirements of the instrument, 

3. Connect one end of the supplied 5 ns coaxial cable to 
the OUTPUT connector on the Type 191. To the other end 
of the coaxial cable, connect the supplied 50 11 termination. 

4. Connect the 50(1 termination to the vertical input 
connector of the oscilloscope. 

5. Apply power to the oscilloscope and allow sufficient 
time for warm up. 



FREQUENCY RANGE 
AMPLITUDE 


50 kHz ONLY 
20 


6. Set the oscilloscope controls as follows: 
Vertical 


VARIABLE Amplitude 


CAL 


Position 


Midrange 


AMPLITUDE RANGE 


5-50 mV 


Norm /invert 


Norm 


POWER 


On 


Variable 


Calibrated 






2-2 




Operating Instructions — Type 191 



Volts/Div 
Input Selector 
Mode Switch 
Time Base 

Triggering Level 

Triggering 

Mode 

Slope 

Coupling 

Source 

Time/Div 

Horizontal 

Horizontal Display 

Position 



0.005 

AC 

To Channel being used 

Set to obtain a stable 
display 

Triggered 

+ 

AC 

Internal Norma! 

2 juSec 

To time base being 
used 

Midrange 



Positions of remaining controls are not important. 

7. Adjust the Triggering Level control on the oscilloscope 
to obtain a stable display. 



8. Change the Type 191 FREQUENCY RANGE switch to 
.35-75. 

9. It may be necessary to readjust the oscilloscope Trig- 
gering Level control to obtain a stable display. 

10. Rotate the Frequency control and note that the signal 
amplitude remains constant while the frequency of the signal 
changes. Remember that the signal amplitude will vary if 
the signal frequency is beyond the 30% down point of the 
oscilloscope. 

11. Rotate the VARIABLE (Amplitude) control clockwise 
and note that the signal amplitude will increase from 20 mV 
to 25 mV. 

12. Return the VARIABLE (Amplitude) control to its CAL 
position. 

13. Change the oscilloscope Volts/Div switch to 0.05 and 
the Type 191 AMPLITUDE RANGE switch to 50-500 mV. The 
display amplitude of the signal has increased 10 times 
although no change in amplitude is noticeable since the 
oscilloscope input attenuation was increased 10 times also. 

14. Rotate the VARIABLE (Amplitude) control clockwise 
and note that the signal amplitude increases from 200 mV 
to 250 mV. 

15. Return the VARIABLE (Amplitude) control to its CAL 
position. 

16. Change the AMPLITUDE switch to 15 and observe that 
the signal amplitude has decreased to 150 mV. 

17. This ends the basic operation procedure for the Type 
191. 



APPLICATION NOTES 

Connection to other Equipment 

Output amplitude regulation is specified with the Type 
191 operating into a 50 ohm load. A 5 nanosecond length 



(about 40 inches) of RG-8A/U coaxial cable (017-0502-00) 
and a 50 ohm termination (01 7-0083-00) are supplied with 
the instrument to provide an optimum environment for amp- 
litude regulation. Shorter lengths of coaxial cable can also 
be used. The terminated coaxial cable should be connected 
directly to the equipment being tested. Any additional length 
of coaxial cable, T-connectors or wire between the 50 ohm 
termination and the equipment being tested will produce 
some variation in the output amplitude. 

A smaller diameter, more flexible output coaxial cable 
(such as RG-58A/U) can be used with the Type 191, but some 
amplitude loss will occur at higher frequencies. For example, 
operating into a 50 ohm load at 100 MHz, a 5 nanosecond 
length of RG-58A/U coaxial cable will produce about a one 
percent amplitude loss as compared to the same length of 
RG-8A/U coaxial cable. 

When the Type 191 is operating into an impedance much 
larger than 50 ohms (essentially open-circuit operation) up to 
twice the maximum terminated output amplitude can be 
obtained. Under this condition, the actual output amplitude 
will be 2 times the indicated amplitude on the front panel. 
The maximum open-circuit amplitude is 11 volts peak to 
peak. Open circuit amplitude regulation is not specified 
but is adequate for many uses, since the Type 191 50 ohm 
output impedance provides a reverse termination for the 
output coaxial cable. The reverse termination tends to keep 
the coaxial cable output amplitude constant even though 
standing waves exist in the coaxial cable. Note that a 5 
nanosecond coaxial cable is a quarter-wavelength at 50 MHz 
and therefore when unterminated presents a short circuit to 
the Type 191. Therefore, the largest difference between 
terminated and unterminated operation will be found on 
the 42-100 MHz range. 

General Equivalent Circuit 

The Type 191 closely approximates a constant voltage 



50 £2 




Fig. 2-3. Equivalent circuit of the Type 191 at the OUTPUT con- 
nector. In the figure V represents the generator output amplitude 
selected with the front-panel controls. 





Operating Instructions — Type 191 



sine-wave generator in series with a 50 ohm resistor, as shown 
in Fig. 2-3. V is the peak-to-peak amplitude selected on the 
front panel. A voltage V will be delivered to a 50 ohm 
load and a voltage 2 V to an open circuit. The addition of 
an unterminated 50 ohm coaxial cable does not change this 
circuit representation. 




When a 50 ohm coaxial cable and termination are con- 
nected to the Type 191, the equivalent circuit becomes that 
shown in Fig. 2-4, a constant voltage generator in series 
with a 25 ohm resistor. 

These equivalent circuits are useful in estimating the 
amplitude changes caused by reactive load impedances. For 
example. Fig. 2-5 shows the circuit for purely capacitive 
loading and the corresponding equation for the output 
amplitude. 



R 






Va 




i 


1 + 


(ft 



where f 0 



1 

2 7T RC 



Fig. 2-4. Equivalent circuit of a Type 191, a 50 ohm cable, and 
a 50 ohm termination. In the figure V represents the generator 
output amplitude selected with the front-panel controls. 



Fig. 2-5. Equivalent circuit for purely capacitive loading. 





SECTION 3 



CIRCUIT DESCRIPTION 



Introduction 

This section of the manual contains an electrical des- 
cription of each circuit in the Type 191. A block diagram 
of the instrument is located in the Diagrams section of this 
manual. The block diagram shows the relationships between 
the circuits of the instrument. 

Schematic diagrams are also located in the Diagrams 
section. These diagrams should be referred to for electrical 
values and relationships of components. 

BLOCK DIAGRAM 

Oscillator 

The Oscillator output signal is supplied to both the Peak 
To Peak Detector and the 50 0 Wideband Attenuator. The 
frequency of the Oscillator is controlled by the FREQUENCY 
RANGE switch and the Frequency dial. The output signal 
amplitude of the Oscillator is controlled by the DC voltage 
applied to the plate of the Oscillator tube VI 0 via the 
Series Regulator tube. This DC voltage is controlled by the 
AMPLITUDE switch and the VARIABLE control settings and 
by the comparison process occuring in the Peak To Peak 
Detector. 



50 £2 Wideband Attenuator 

The 50 Q Wideband Attenuator takes the normal 1 to 1 1 
volt signal supplied from the Oscillator and, depending 
upon the AMPLITUDE RANGE switch setting, either supplies 
the signal through 50 ohms to the OUTPUT connector (.5-5V), 
attenuates the signal 10X (50-500 mV), or attentuates the 
signal 100X (5-50 mV). 

The output resistance of the Type 191 is 50 ohms in all 
positions of the AMPLITUDE RANGE switch. 



Comparison Voltage 

The DC voltage from the Comparison Voltage circuit 
applied to the Peak To Peak Detector determines the Oscil- 
lator output signal amplitude applied to the 50 0 Wideband 
Attenuator. 



Peak To Peak Detector 

The output of the Oscillator and the Comparison Voltage 
are compared in the Peak To Peak Detector and any neces- 
sary correction voltage to correct the output signal amplitude 
is sent to the Feedback DC Amplifier. 

Feedback DC Amplifier 

This amplifier recieves the correction voltage from the 
Peak To Peak Detector and then supplies the amplified 
correction voltage to the grid of V94, the Series Regulator 
Tube. 



Series Regulator 

The correction voltage from the Feedback DC Amplifier 
varies the grid potential of V94, which causes the Series 
Regulator tube to adjust the amount of plate voltage avail- 
able to the Oscillator tube. 



Unregulated Power Supply 

The Unregulated Power Supply makes available about 
+450 volts of DC voltage to the plate of the Series Regula- 
tor tube, V94. 

DETAILED CIRCUIT DESCRIPTION 
Oscillator 

Oscillator tube VI 0 is connected as a grounded cathode 
Class C Colpitts Oscillator. Plate current is supplied to the 
grid end of switched inductors through R90, R99, R98, L98 
and Zener diode D98. L98 and resistors R98, R99 and R90 
isolate the Oscillator from the low output impedance of the 
Series Regulator, thereby increasing the Q of the Oscillator 
circuit. Zener diode D98 provides a voltage drop to furnish 
Q94 with sufficient collector voltage when the Oscillator 
output amplitude is minimum. 

Feedback to the grid of VI 0 to maintain oscillations is 
provided from the grid end of the switched inductors through 
C8 and R8. 

The tuning capacitor (Frequency dial) for the Oscill- 
ator is composed of C10A, B, C and D. Sections C10A, B 
and C of the tuning capacitor are electrically connected in 
parellet in the grid circuit while only section C10D of the 
tuning capacitor is connected to the plate circuit. This per- 
mits the ratio of plate to grid AC voltage to be 3 to 1. 

The switched inductors which provide the various fre- 
quency ranges have adjustable powdered iron slugs and 
individual trimmer capacitors. These adjustments permit the 
frequency span of each range Jo be accommodated to the 
precalibrated dial. The selection of inductor is determined 
by the FREQUENCY RANGE switch, SW10. 

The switched inductor for the 50 kHz ONLY range also has 
an adjustable powdered iron slug. Large fixed capacitors 
are connected in parallel with CIO to reduce the necessary 
inductance for 50 kHz operation. The large capacitors result 
in a negligible frequency difference (less than ±1%) from 
50 kHz at any setting on the frequency dial. 

The ferrite beads LI 1 and LI 2 mounted on the leads of 
T10 minimize high frequency currents induced when the 
oscillator is operating in the 42 MHz to 100 MHz range. 

The individually switched output coils, inductively coupled 
to the oscillator coils, provide oscillator signal to the output 
networks. The inductor and capacitor in each of the output 
networks except for the 42 to 100 MHz range output coil, 
constitute low pass filter which partially removes the higher 
frequency harmonics from the output oscillator signal. The 



I 



®l 



3-1 



Circuit Description — Type 191 



resistor in each of the output networks except for the 42 to 
100 MHz range reduces the Q of the resonant circuit which is 
formed by the components of the output network. Low Q is 
necessary for minimum disturbance of the Oscillator. The 
resistor and capacitor on the 42 to 100 MHz range constitute 
a low pass filter. The inductor reduces the amount of cap- 
acitance presented to the Oscillator circuit when the Type 
191 OUTPUT connector is unterminated. 

Toroid L64 located on the coaxial cable from the output 
point to the sampling point/ reduces the amount of stray 
radio frequency current flowing in the shield of the coaxial 
cable. 



50 12 Wideband Attenuator 

The Oscillator signal at the sampling point goes two ways. 
One path is through R40 to the 50 Cl Wideband Attenuator. 
The 50 ohm output impedance of the Oscillator is set by R40. 
This is true because the steady state impedance of the sam- 
pling point approaches zero ohms. 

In all positions of the AMPLITUDE RANGE switch, both the 
input and output impedances of the 50 Cl Wideband Attenu- 
ator are 50 ohms. This is accomplished by the impedance of 
R40 and the 50 ohm T section attenuators. Each of the T 
section attenuators is stacked, i.e., the .5-5 V range has no 
signal attenuation ahead of the OUTPUT connector, while 
the 50-500 mV range has 10 times signal attenuation and the 
5-50 mV range has 100 times signal attenuation. 

The AMPLITUDE RANGE switch positions are labeled to 
indicate the output signal amplitude range, when the Type 
191 OUTPUT connector is properly terminated into 50 ohms. 

Toroid L49, located on the coaxial cable from the output 
of the 50 0 Wideband Attenuator to the OUTPUT connector, 
reduces the amount of stray radio frequency current flowing 
in the shield of the coaxial cable. 



Comparison Voltage 

The Comparison Voltage circuit is a Kelvin- Varley divider. 
The voltage picked off from the divider, which is determined 
by the AMPLITUDE switch position, is applied across the 
VARIABLE control R58. The output voltage from R58 is fed 
to point C of the circuit board (Peak To Peak Detector 
circuit). 

To obtain, for example, a 5 volt peak-to-peak Oscillator 
signal at the sampling point the output voltage from the 
Comparison Voltage circuit must be — 5 volts. 

TRACKING (R55) and AMPL CAL (R51) controls adjust the 
divider so the Oscillator output amplitude will agree with 
the front panel labeling. The AMPLITUDE switch and VARI- 
ABLE control labels indicate, in conjunction with the AMPLI- 
TUDE RANGE switch, the output signal amplitude when 
the Type 191 OUTPUT connector is properly terminated into 
50 ohms. 



Peak To Peak Detector 

The function of the Peak to Peak Detector is to provide a 
DC voltage to the Feedback DC Amplifier which represents 
the difference between the DC comparison voltage and the 



actual peak-to-peak voltage (Oscillator output amplitude) 
at the sampling point. The output of the detector under 
steady conditions is a DC voltage established at the junction 
of R71 and the base of Q74. 

For a first analysis of the Peak To Peak Detector operation, 
diodes D60 and D67 will be assumed to be ideal; that is, 
when conducting they have zero voltage drop across them. 
Now, assume that the comparison voltage is — 10 volts. The 
peak-to-peak voltage will also be 10 volts because of the 
action of the Feedback DC Amplifier and Series Regulator. 
When the output sine wave is at its most negative point, 
—5 volts, the junction of D60 and D67 will be at —10 volts. 
When the Oscillator output sine wave is at its most positive 
point, +5 volts, the junction of D60 and D67 will be at zero 
volts. The detector output under these conditions will there- 
fore be zero volts, since C66 and C67 will charge to the most 
positive voltage appearing on the anode of D67. In other 
words, C63 and C64 pass the sine wave at full amplitude 
to the junction of D60 and D67, but displace it negatively 
by a DC voltage equal to one-half the Oscillator output 
peak-to-peak amplitude. The waveform at the junction of 
D60 and D67 varies, therefore, from — 10 volts to zero volts. 
Since the detector output must supply a direct current of 
about IOjuA whose source is the charge stored in C63 and 
C64, these capacitors must receive periodic charging currents. 
During the time D67 is conducting (at the positive Oscillator 
output sine wave peak), the charge passes from C63 and 
C64 to C66 and C67. This charge removal from C63 and 
C 64 is replaced at the negative Oscillator sine wave peak 
when D60 conducts momentarily. The charge gained by C63 
and C64 at each negative peak is exactly equal to the 
charge lost at each positive peak. If for any reason the 
Oscillator output amplitude changes, a corresponding change 
in the detector output will provide an error signal to the 
Feedback DC Amplifier which will act to restore the ampli- 
tude to its correct value. 

If the comparison voltage is changed, the feedback 
circuit will act to make the Oscillator output amplitude 
change the same amount. 

When D60 and D67 are real instead of ideal diodes, with 
forward voltages of about 0.6 volts each, the actual detector 
output voltage is —1.2 volts instead of zero volts for the 
description given above. The differential amplifier consist- 
ing of Q74 and Q84 is arranged to accept this voltage 
by having the base of Q84 offset about —1 .2 volts by means 
of D80, D81 and R80. 

C60, C64, and C67 are disc capacitors with low inductance 
connections to readily pass high frequency current pulses. 
C61, C63, and C66 are larger capacitors to provide more 
charge storage at lower frequencies. Ferrite beads L61, L63, 
and L66 provide damping for the capacitors on which they 
are mounted. R60-C60 and R67-C67 are low-pass filter 
networks and R64 is a damping resistor. Toroid L70 mini- 
mizes stray radio frequency current in the coaxial cable 
shield. 



Feedback DC Amplifier 

The current output of the Peak To Peak Detector deter- 
mines a voltage at the base of Q74. The voltage at the 
base of Q74 is compared to the voltage at the base of Q84, 
the other half of a differential amplifier. The voltage at the 



3-2 







Circuit Description — Type 191 



base of Q84 is determined by the combined junction volt- 
ages of D80 and D81 and by the current through R80 and 
R81. The difference in voltage between the two inputs to the 
differential amplifier determines the voltage presented at the 
base of emitter follower Q93. From the emitter follower Q93 
the signal is fed to the base of common emitter amplifier 
Q94. The output voltage of Q94 is then fed to the grid of 
V94, part of the Series Regulator circuit. 

A differential amplifier is used as part of the Feedback 
DC Amplifier so temperature compensated DC voltage ampli- 
fication can be obtained without inversion. The inversion in 
the Feedback Amplifier is due to the common emitter ampli- 
fier stage. The overall gain of the Feedback DC Amplifier 
is about 100,000. 

Any temperature or DC offset voltage variations in the 
voltage at the base of Q74 caused by the Peak To Peak 
Detector or sampling diodes D60 and D67, is compensated 
for in the Feedback DC Amplifier by diodes D80 and D81, 
located in the base circuit of Q84. Diodes D80 and D81 
introduce a temperature dependent voltage on the base of 
Q84 which approximately matches the temperature depend- 
ent voltage on the base of Q74 caused by the sampling 
diodes D60 and D67. D80 and D81 also provide an offset 
voltage to match the detector output. 

R72 and C72 decrease the AC voltage gain of the Feed- 
back DC Amplifier to prevent oscillation. 

R70 and C71 comprise a low pass filter to bypass radio 
frequency voltage components to ground at the amplifier 
input. 

Series Regulator 

The output voltage of the Feedback DC Amplifier is fed 
to the control grids of Series Regulator tube V94 where it 
controls the conduction of V94. By varying the grid volt- 
age of V94 (connected as a cathode follower), the amount of 
plate voltage available to the Oscillator tube VI 0 can be 
controlled, thereby controlling the output signal amplitude 
of the Oscillator. 

During the initial warm-up time of V94 after the instru- 
ment has been turned on, D94 prevents a high positive 
voltage from appearing on the grid with respect to the 
cathode. If such a large electric field were repeatedly 
applied to a cold cathode, cathode damage would eventu- 
ally occur. R97 prevents a charge being stored on the 
cathodes of V94 after the instrument has been turned off. 

R95 and R96 prevent parasitic oscillation in V94. 



Power Supply 

Primary. Power is applied to the instrument through 
PI 01. Line filter Cl 01 -Cl 02 reduces the effect on the power 
line of signals generated in the instrument. SW105, as 



connected at the factory, permits the instrument to be easily 
converted from 115 volts to 230 volts by connecting the two 
transformer primaries in parallel for 115 volt operation or 
by connecting the two transformer primaries in series for 
230 volt operation. 

+ 6.2 and — 11 Volt Supply. Output from transformer 
T101 is rectified by diodes D112A and D112B resulting in 
about 40 volts being applied across the parallel network of 
Cl 13 and R1 17-D1 17-D1 18-R1 15. Output from the same 
winding of T101 is also rectified by D112C and Dll 2D 
resulting in about 40 volts being applied across the parallel 
network of Cl 15 and R115-R118. The output from diodes 
D112A and D112B supplies Zener diode Dll 7 with current. 
Zener diode Dll in conjunction with Dll 8, R115 and R118 
then establishes a voltage of +6.2 volts at the junction of 
D1 17 and R1 17. 

Dll 8 is connected in series with D117 to provide a tem- 
perature compensation for the +6.2 volt supply. 

R115 and R118 provide compensation for any change in 
line voltage that might cause a current change in D117 and 
Dll 8. This current change through the dynamic resistance 
of D117 and D118 (about 15 ohms total) will produce a volt- 
age change across the two diodes. R115 and R118 introduce 
a voltage of opposite polarity to the cathode of Dll 8 which 
offsets the change across Dll 7 and Dll 8. This compensa- 
tion is established so the characteristic of the +6.2 volt 
supply acting together with the operational amplifier in the 
— 11 volt supply produces minimum change in the — 11 volt 
output as the line voltage varies. 

The +6.2 volts is supplied to the input of an operational 
amplifier stage consisting of Q123 and Q127. The opera- 
tional amplifier stage has a gain of about —1.8, which is 
adjustable. The input resistor of the operational amplifier 
is R120 and the feedback resistance is made up of R121 and 
R122 in series. The connection of the two transistors of the 
operational amplifier stage provides temperature comp- 
ensation for the emitter-base voltages. 

The +6.2 volts which is supplied to the operational ampli- 
fier stage is inverted and amplified to obtain the —11 volts. 
The —11 VOLTS control R122 adjusts the gain of the opera- 
tional amplifier and therefore the output voltage. The 
stable —11 volts is then used as the reference supply for 
the signal amplitude. 

+ 450 Volt Supply. Output from transformer T101 is 
rectified by D132A, B, C and D and applied across C132A 
and B for an unregulated output voltage of +450 volts. 
R140 and R135 are bleeder resistors for the supply; R140 
discharges the filter capacitor when the POWER switch has 
been turned off. If, however, the instrument has had the line 
power removed but the Power switch remains on, then R135 
discharges the filter capacitor, but at a slower rate. 

R137 and R138 elevate the heater of V94 to approximately 
180 volts to minimize heater-to-cathode leakage. 




NOTES 





SECTION 4 
MAINTENANCE 



Introduction 

This section of the manual contains maintenance infor- 
mation for use in preventive maintenance, corrective main- 
tenance or troubleshooting of the Type 191. 

PREVENTIVE MAINTENANCE 

General 

Preventive maintenance consists of cleaning, visual 
inspection, lubrication, etc. Preventive maintenance per- 
formed on a regular basis will help prevent instrument 
failure and will improve reliability of this instrument. The 
severity of the environment to which the Type 191 is sub- 
jected will determine the frequency of maintenance. 

Cleaning 

The Type 191 should be cleaned as often as operating 
conditions require. Accumulation of dirt in the instrument 
can cause overheating and component breakdown. Dirt 
on components acts as an insulating blanket and prevents 
efficient heat dissipation. It also provides an electrical 
conduction path. 

The cover provides protection against dust in the interior 
of the instrument. Operation without the cover in place 
will mean more frequent cleaning is required. 

CAUTION 

Avoid the use of chemical cleaning agents which 

might damage the plastics used in this instrument. 

Some chemicals to avoid are benzene, toluene, 

xylene, acetone or similar solvents. 

Exterior. Loose dust accumulated on the outside of 
the Type 191 can be removed with a soft cloth or small 
paint brush. The paint brush is particularly useful for dis- 
lodging dirt on and around the front-panel controls. Dirt 
which remains can be removed with a soft cloth dampened 
in a mild solution of water and detergent. Abrasive clean- 
ers should not be used. 

Interior. Dust in the inferior of the instrument should 
be removed occasionally due to its electrical conductiv- 
ity under high-humidity conditions. The best way to clean 
the interior is to blow off the accumulated dust with dry, 
low-velocity air. Remove any dirt which remains with a 
soft paint brush or a cloth dampened with a mild deter- 
gent and water solution. A cotton-tipped applicator is 
useful for cleaning in narrow spaces or for cleaning ceramic 
terminal strips and circuit board. 

Lubrication 

The reliability of potentiometers, rotary switches and 
other moving parts can be increased if they are kept prop- 
erly lubricated. Use a cleaning-type lubricant (such as Tek- 
tronix Part No. 006-0218-00) on shaft bushings and switch 



contacts. Lubricate switch detents with a heavier grease 
(such as Tektronix Part No. 006-0219-00). Potentiometers 
should be lubricated with a lubricant which will not affect 
electrical characteristics (such as Tektronix Part No. 006- 
0220-00). Do not over lubricate. A lubrication kit contain- 
ing the necessary lubricants and instructions is available 
from Tektronix. Order Tektronix Part No. 003-0342-00. 

Visual Inspection 

The Type 191 should be inspected occasionally for 
such defects as broken connections, broken or damaged 
ceramic strips, improperly seated transistors or tubes, dam- 
aged circuit board and heat-damaged parts. 

The remedy for most visible defects is obvious; however, 
care must be taken if heat-damaged parts are located. 
Overheating is usually only a symptom of trouble. For 
this reason, it is essential to determine the actual cause 
of overheating before the heat-damaged part is replaced; 
otherwise, the damage may be repeated. 

Transistor and Tube Checks 

Periodic checks of the transistors and tubes in the Type 
191 are not recommended. The best check of transistor or 
tube performance is its actual operation in the instrument. 
More details on checking transistor and tube operation is 
given under Troubleshooting. 

Recalibration 

To assure accurate measurements, check the calibration 
of this instrument after each 500 hours of operation or 
every six months if used infrequently. Complete instruc- 
tions are given in the Calibration section. 

The calibration procedure can also be helpful in local- 
izing certain troubles in the instrument. In some cases minor 
troubles, not apparent during normal use, may be revealed 
and/or corrected by recalibration. 

CORRECTIVE MAINTENANCE 

General 

Corrective maintenance consists of component replace- 
ment and instrument repair. Special techniques or proce- 
dures required to replace components in this instrument are 
described here. 

Obtaining Replacement Parts 

Standard Parts. All electrical and mechanical part 
replacements of the Type 191 can be obtained through 
your local Tektronix Field Office or representative. How- 
ever, many of the standard electronic components can be 
obtained locally in less time than is required to order them 
from Tektronix, Inc. Before purchasing or ordering replace- 
ment parts, consult the Parts List for value, tolerance and 
rating. 






4-1 




Maintenance — Type 191 



NOTE 

When selecting replacement parts, it is important 
to remember that the physical size and shape of 
a component may affect its performance at high 
frequencies. All replacement parts should be 
direct replacements unless it is known that a dif- 
ferent component will not adversely affect instru- 
ment performance. 

Special Parts. In addition to the standard electronic 
components, some special parts are used in the Type 191. 
These parts are manufactured or selected by Tektronix, 
Inc. to meet specific performance requirements/ or are 
manufactured for Tektronix, Inc. in accordance with our 
specifications. These special parts are indicated in the 
Parts List by an asterisk preceding the part number. Most 
of the mechanical parts used in this instrument have been 
manufactured by Tektronix, Inc. Order all special parts 
directly from your Tektronix Field Office or representative. 

Ordering Parts. When ordering replacement parts from 
Tektronix, include the following information: 

1. Instrument Type. 

2. A description of the part (if electrical, include circuit 
number). 

3. Tektronix Part Number. 

4. Instrument Serial Number. 



Soldering Techniques 

WARNING 

Disconnect the instrument from the power source 

before soldering. 

Circuit Board. Use ordinary 60/40 solder and a 35- to 
40-watt pencil type soldering iron on the circuit board. The 
tip of the iron should be clean and properly tinned for best 
heat transfer to the solder joint. A higher wattage soldering 
iron may separate the circuit from the base material. 

The following technique should be used to replace a 
component on a circuit board. Most components can be 
replaced without removing the board from the instrument. 

1. Grip the component lead with long-nose pliers. Touch 
the soldering iron to the lead at the solder connection. 
Do not lay the iron directly on the board. 

2. When the solder begins to melt, pull the lead out 
gently. This should leave a clean hole in the board. If 
not, the hole can be cleaned by reheating the solder and 
placing a sharp object such as a toothpick or pointed tool 
into the hole to clean it out. 

3. Bend the leads of the new component to fit the holes 
in the board. If the component is replaced while the board 
is mounted in the instrument, cut the leads so they will 
just protrude through the board. Insert the leads into the 
holes until the component is firmly seated against the 
board. If it does not seat properly, heat the solder and 
gently press the component into place. 



4. Apply the iron and a small amount of solder to the 
connection to make a firm solder joint. To protect heat- 
sensitive components, hold the lead between the compo- 
nent body and the solder joint with a pair of long-nose 
pliers or other heat sink. 

5. Clip the excess lead that protrudes through the board. 

6. Clean the area around the soldered connection with 
a flux-remover solvent, being careful not to remove infor- 
mation printed on the board. 

Ceramic Terminal Strips. Solder used on the ceramic 
terminal strips should contain about 3% silver. Ordinary 
tin-lead solder can be used occasionally without damage 
to the ceramic terminal strips. Use a 40- to 75-watt sol- 
dering iron with a % inch wide chisel-shaped tip. If ordinary 
solder is used repeatedly or if excessive heat is applied, 
the solder-to-ceramic bond may be broken. 

A small roll of 3% silver solder is mounted on the main 
chassis. Additional silver solder should be available local- 
ly or it can be purchased directly from Tektronix; order 
by Tektronix Part No. 251-0514-00. 

Observe the following precautions when soldering ceramic 
terminal strips: 

1. Use a hot iron for a short time. Apply only enough 
heat to make the solder flow freely. 

2. Maintain a clean, properly tinned tip. 

3. Avoid putting pressure on the ceramic terminal strip. 

4. Do not attempt to fill the terminal-strip notch with 
solder; use only enough solder to cover the wires ade- 
quately. 

5. Clean the flux from the terminal strip with a flux- 
remover solvent. 

Metal Terminals. When soldering metal terminals (e.g., 
switch terminals, potentiometers, etc.) ordinary 60/40 solder 
can be used. The soldering iron should have a 40- to 75- 
watt rating with a % inch wide chisel-shaped tip. 

Observe the following precautions when soldering metal 
terminals: 

1. Apply only enough heat to make the solder flow 
freely. 

2. Apply only enough solder to form a solid connec- 
tion. Excess solder may impair the function of the part. 

3. If a wire extends beyond the solder joint, clip off 
the excess. 

4. Clean the flux from the solder joint with a flux- 
remover solvent. 

Component Replacement 

WARNING 

Disconnect the instrument from the power source 

before replacing components. 

Removing Covers. The cover is held in place by a 
slotted thumb screw located on the front-panel of the instru- 




Maintenance — Type 191 



merit. To remove the cover, loosen the slotted thumb screw 
and slide the cover off of the instrument. 

Ceramic Terminal Strip Replacement. A complete 
ceramic terminal strip assembly is shown in Fig. 4-1. Replace- 
ment strips (including studs) and spacers are supplied under 
separate part numbers. The old spacers may be re-used 
if they are not damaged. 



No,ch i^innnnjruinn 

Ceramic Strip 



/ 









-Stud 



Chassis 



Spacer 



V 

x Stud Pin 



Fig. 4-1 . Ceramic terminal strip assembly. 



To replace a ceramic terminal strip, first unsolder all 
connections. Then, the damaged strip can be pried or 
pulled loose from the chassis. If the spacers come out with 
the strip, remove them from the stud pins to be used for 
installation of the new strip. 

After the damaged strip has been removed, place the 
undamaged spacers in the chassis holes. Then, carefully 
press the studs into the spacers until completely seated. 
If necessary, use a soft mallet and tap lightly directly over 
the stud area of the strip. 

Circuit Board Replacement. If the circuit board is dam- 
aged and cannot be repaired, the entire assembly includ- 
ing all soldered-on components should be replaced. The 
part number given in the Mechanical Parts list is for the 
completely-wired board. 

Procedure for replacing circuit board follows: 

Removal. All except three connections to the circuit board 
are push on connections. The remaining connections are 
soldered. 

Most of the components mounted on the circuit board 
can be replaced without removing the board from the 
instrument. Observe soldering precautions given under 

Soldering Techniques in this section. However, if the 
board must be moved to gain access to other areas of the 
instrument, only the mounting screws need be removed 
and the three solder connections unsoldered. The inter- 
connecting wires will allow the board to be moved out 
of the way or turned over. 

Use the following procedure to remove a board: 

1. Disconnect all pin connectors and the coaxial con- 
nector, all of which come through holes in the board. 



2. Unsolder the ground wire which connects T14 to the 
board. 

3. Remove all screws holding the board to the chassis. 

4. Unsolder the two ground wires and the resistor con- 
necting the board to the AMPLITUDE RANGE switch. 

5. The board may now be lifted and removed for main- 
tenance or access to areas beneath the board. 

6 . To replace the board, reverse the order of removal. 

Transistor and Tube Replacement. Transistors and tubes 
should not be replaced unless actually defective. If removed 
during routine maintenance, return them to their original 
sockets. Unnecessary replacement of transistors or tubes 
may affect the calibration of this instrument. When tran- 
sistors or tubes are replaced, check the operation of that 
part of the circuit which may be affected. 

Replacement transistors or tubes should be of the original 
type or a direct replacement. 

To replace V10: 

1. Slide the tube shield away from the tube socket base 
as far as possible. 

2. Remove the tube from the tube socket. 

3. Slide the tube back into the tube shield. 

4. Remove the tube and tube shield from the Type 191 
as a unit. 

5. Remove the tube from the tube shield. 

6. Install the replacement tube into the tube shield. 

7. Place the tube and tube shield into the instrument 
aligning it for insertion into the tube socket. 

8. Slide the tube part way out of the shield. 

9. Seat the tube into the tube socket. 

10. Slide the tube shield onto the tube socket base. 

Fuse Replacement. The line fuse is located on the rear 
panel. Table 2-1 in this manual gives the fuse value for the 
different line voltages. 

Rotary Switches. Individual wafers or mechanical parts 
of rotary switches are normally not replaced. If a switch 
is defective, replace the entire assembly. Replacement 
switches can be ordered either wired or unwired; refer to 
the Electrical Parts List for the applicable part numbers. 

When replacing a switch, it is recommended that the 
leads and switch terminals be tagged with corresponding 
identification tags as the leads are disconnected. Then, 
use the old switch as a guide for installing the new one. 
An alternative method would be to draw a sketch of the 
switch layout and record the wire color at each terminal. 

TROUBLESHOOTING 



Introduction 

The following information is provided to facilitate trouble- 
shooting of the Type 191. Information contained in other 
sections of this manual should be used along with the fol- 
lowing information to aid in locating the defective com- 
ponent. 



®T 



4-3 




Maintenance — Type 191 



Troubleshooting Aids 

Diagrams. Circuit diagrams are given on foldout pages 
in Section 9. The circuit number and electrical value of 
each component in this instrument are shown on the dia- 
grams. Important voltages and waveforms are also shown 
on the diagrams. 

Component Numbering. The circuit number of each 
electrical part is shown on the circuit diagram. Each main 
circuit is assigned a series of circuit numbers. Table 4-1 
lists the main circuits in the Type 191 and the series of 
circuit numbers assigned to each. For example, using Table 
4-1, a resistor numbered R120 is identified as being located 
in the Power Supply. 

TABLE 4-1 

Circuit Numbers 



on Diagrams 




Circuit 


1-99 1 




Signal Generator 


100-199 




Power Supply 


Switch Wafer Identification. 


Switch wafers shown on 



the diagrams are coded to indicate the position of the 
wafer in the complete switch assembly. The numbered 
portion of the code refers to the wafer number counting 
from the front, or mounting end of the switch, toward the 
rear. The letters F and R indicate whether the front or 
rear of the wafer performs the particular switching func- 
tion. For example, a wafer designated 2R indicates that 
the rear of the second wafer is used for this particular 
switching function. 

Circuit Boards. Fig. 4-3 shows the circuit board used in 
the Type 191. Each electrical component on the board 
is identified by its circuit number. The circuit board is also 
outlined on the diagram with a blue line. This picture along 
with the diagram will aid in locating the components 
mounted on the circuit board. 




Fig. 4-2. Color-coding of metal-film resistors. 

Wiring Color-Code. All insulated wire used in the Type 
191 is color-coded according to the EIA standard color- 
code (as used for resistors) to facilitate circuit tracing. The 
widest color stripe identifies the first color of the code. 
Power-supply voltages can be identified by three color 
stripes and the following background color-code; white, 
positive voltage; tan, negative voltage. Table 4-2 shows 
the wiring color-code for the power-supply voltages used 
in the Type 191. The remainder of the wiring in the Type 



191 is color-coded with two or less stripes or has a solid 
background with no stripes. The color-coding helps to 
trace a wire from one point in the instrument to another. 

TABLE 4-2 



Supply 


Back- 

ground 

Color 


1st 

Stripe 


2nd 

Stripe 


3rd _ 

Stripe 


-11 volt 


Tan 


Brown 


Brown 


Black 


+6.2 volt 


White 


Blue 


Red 


Black 


+450 volt 


White 


| Yellow 


i Green 


Brown 



Resistor Color-Code. A number of precision metal-film 
resistors are used in this instrument. These resistors can 
be identified by their gray body color. If a metal-film 
resistor has a value indicated by three significant figures 
and a multiplier, it will be color-coded to the EIA standard 
resistor color-code. If it has a value indicated by four sig- 
nificant figures and a multiplier, the value will be printed 
on the body of the resistor. For example, a 333 k Cl resistor 
will be color-coded, but a 333.5 kll resistor will have its 
value printed on the resistor body. The color-code sequence 
is shown in Fig. 4-2. 

Composition resistors are color-coded according to the 
EIA standard resistor color-code. 

Troubleshooting Techniques 

This troubleshooting procedure is arranged in an order 
which checks the simple trouble possibilities before pro- 
ceeding with extensive troubleshooting. The first few checks 
assure proper connection, operation and calibration. If the 
trouble is not located by these checks, the remaining steps 
aid in locating the defective component. When the defec- 
tive component is located, it should be replaced follow- 
ing the replacement procedures given in this section. 

1. Check Associated Equipment. Before proceeding 
with troubleshooting of the Type 191, check that the equip- 
ment used with the Type 191 is operating correctly. Check 
that the signal is properly connected and that the inter- 
connecting cable is not defective. Also, check the power 
source. 

2. Check Control Settings. Incorrect control settings 
can indicate a trouble that does not exist. For example, 
incorrect setting of the VARIABLE control appears as an 
uncalibrated signal amplitude; incorrect setting of the Fre- 
quency dial appears as a misadjusted Oscillator circuit, 
etc. If there is any question about the correct function or 
operation of any control, see the Operating Instructions 
section of this manual. 

3. Check Instrument Calibration. Check the calibra- 
tion of the instrument, or the affected circuit if the trouble 
exists in one circuit. The indicated trouble may only be 
a result of misadjustment or may be corrected by calibra- 
tion. Complete instructions are given in the Calibration 
section of this manual. Individual calibration steps can be 
performed out of sequence. However, if the circuit affects 
the calibration of other circuits in the instrument, a more 
complete calibration will be necessary. General Informa- 
tion in the Calibration section describes how calibration 
steps which interact are noted. 



® 



4-4 





Maintenance — Type 191 



4. Isolate Trouble to a Circuit. To isolate a trouble 
to a circuit, note the trouble symptom. The symptom often 
identifies the circuit in which the trouble is located. For 
example, incorrect frequency indicates that the Oscillator 
circuit is probably at fault. Methods of checking the cir- 
cuits are given in steps 5 through 7. 

Incorrect operation of all circuits often indicates trouble 
in the Power Supply. Check first for correct voltage at 
each of the individual supplies. However, a defective com- 
ponent elsewhere in the instrument can appear as a power 
supply trouble and may also affect the operation of other 
circuits. 

Table 4-3 lists the typical values of the power supplies 
in the Type 191. If a power supply voltage is within the 
listed value, the supply can be assumed to be working 
correctly. If outside the value, the supply may be operat- 
ing incorrectly. Use the procedure given in the Calibra- 
tion section to adjust the —11 volt power supply. 



TABLE 4-3 



Power Supply 


Typical Value 


—11 volt 


+0.2 V 1 


+6.2 volt 


±0.4 V 


+450 volt 


Unregulated 



^Adjusted for correct output signal amplitude. 

After the defective circuit has been located, proceed 
with steps 5 through 7 to locate the defective component(s). 
If the trouble has not been isolated to a circuit using the 
procedure described here, check voltage and waveforms 
as explained in step 6 to locate the defective circuit. 

5. Visual Check. Visually check the circuit in which 
the trouble is located. Many troubles can be located by 
visual indications such as unsoldered connections, broken 
wires, damaged circuit boards or damaged components. 

6. Check Voltages and Waveforms. Often the defec- 
tive component can be located by checking for the correct 
voltage or waveform in the circuit. Typical voltages and 
waveforms are given on the Diagrams. 

NOTE 

Voltages and waveforms given on the diagrams 
are not absolute and may vary slightly between 
instruments. To obtain operating conditions similar 
to those used to take these readings, see the 
first diagram page for conditions under which 
voltages and waveforms are taken. 

A. Voltages. Voltage measurements should be taken 
with a 20,000 ohms/volt DC voltmeter. Accuracy of the 
voltmeter should be within 3% on all ranges. Be sure that 



the test prods are well insulated to prevent accidental short- 
ing of components. 

B. Waveforms. Use a test oscilloscope which has the 
following minimum specifications: 

Bandwidth: DC to at least 40 MHz. 

Deflection factor: 0.05 volts/division minimum. 

Input impedance: Approximately 10 megohms paralleled 
by about lOpF when using a 10X probe. 

7. Check Individual Components. The following pro- 
cedures describe methods of checking individual compo- 
nents in the Type 191. Components which are soldered in 
place can be checked most easily by disconnecting one 
end. This eliminates incorrect measurements due to the 
effects of surrounding circuitry. 

A. Transistors and Tubes. The best check of transistor 
or tube operation is actual performance under operating 
conditions. If a transistor or tube is suspected of being 
defective, it can best be checked by substituting a new 
component or one which has been checked previously. 
However, be sure that circuit conditions are not such that 
a replacement transistor or tube might also be damaged. 
If substitute transistors or tubes are not available, a dynamic 
tester may be used (such as Tektronix Type 570 or 575). 
Static-type testers are not recommended, however, since 
they do not check operation under simulated operating 
conditions. 

B. Diodes. A diode can be checked for an open or 
shorted condition by measuring the resistance between 
terminals. With an ohmmeter scale having an internal 
source of about 1.5 volts, the resistance should be very high 
in one direction and very low when the leads are reversed. 

CAUTION 

Do not use an ohmmeter scale that has a high 

internal current. High currents may damage the 

diode. 

C. Resistors. Resistors can be checked with an ohm- 
meter. Check the Electrical Parts list for the tolerance of 
the resistors used in this instrument. Resistors normally do 
not need to be replaced unless the measured value varies 
widely from the specified value. 

D. Inductors. Check for open inductors by checking con- 
tinuity with an ohmmeter. 

E. Capacitors. A leaky or shorted capacitor can best 
be detected by checking resistance with an ohmmeter on 
the highest scale. Do not exceed the voltage rating of 
the capacitor. The resistance reading should be high after 
initial charge of the capacitor. An open capacitor can best 
be detected with a capacitance meter or by checking 
whether the capacitor passes AC signals. 






4-5 




Maintenance — Type 191 




Fig. 4*9. F»ok to peok d«t«ctor bootd wiring. 



®! 



4-6 





SECTION 5 

PERFORMANCE CHECK 



Introduction 

This performance check procedure is provided to check 
the operation of the Type 191. This procedure may be used 
for incoming inspection, instrument familiarization, reliability 
testing, calibration verification, etc. 

Failure to meet characteristics given in the procedure 
indicates that the instrument requires internal checks and/or 
adjustments. See the Calibration section of the Instruction 
Manual. 



EQUIPMENT REQUIRED 



General 

The following equipment, or its equivalent, is required for 
a complete performance check of the Type 191. Specifications 
given are the minimum necessary to accurately check the per- 
formance of this instrument. All test equipment is assumed 
to be correctly calibrated and operating within the original 
specifications. If equipment is substituted, it must meet or 
exceed the specifications of the recommended equipment. 



Special Test Equipment 

For the quickest and most accurate calibration, special 
calibration fixtures are used where necessary. All calibra- 
tion fixtures listed under Equipment Required can be obtained 
from Tektronix, Inc. Order by part number through your 
local Tektronix Field Office or representative. 

1. Real-time test oscilloscope. Bandwidth, DC to lOMHz; 
minimum deflection factor, 0.005 volts/division. Tektronix 
Type 547 Oscilloscope with Type 1A1 plug-in unit or equiv- 
alent. 

2. Sampling test oscilloscope. Bandwidth, equivalent to 
DC to 1000 MHz; minimum deflection factor, 5 millivolts/ 
division. Tektronix Type 661 Oscilloscope with a Type 4S3 
vertical plug-in and a Type 5T3 timing plug-in. 

3. Standard amplitude calibrator. Amplitude accuracy, 
within dzO.25%; signal amplitude, 0.01 volts to 2 volts; out- 
put frequency, 1 kHz. Tektronix calibration fixture 067-0502- 
00 or equivalent. 

4. Time-mark generator. Marker outputs of 1 jjls, 5 jjls, 
and 10 /as; sine wave outputs of 20 ns and 50 ns; accuracy, 

0.001%. Tektronix Type 184 or equivalent. 

5. Variable autotransformer. Must be capable of sup- 
plying at least 25 watts to the Type 191 over a voltage 
range of 94 to 138 volts (188 to 276 volts for 230-volt nomi- 
nal line). If autotransformer does not have an AC voltmeter 
to indicate output voltage, monitor output with an AC volt- 
meter (rms) with range of at least 138 (or 276) volts. For 
example, General Radio W10MT3W Metered Variac Auto- 
transformer. 

6. Two 50 ohm voltage pickoff units. Tektronix VP-1 and 
VP-2 or their equivalents. 



7. Termination. Impedance 50 ohm; accuracy, ±1%; con- 
nectors, BNC jack to GR. Tektronix Part No. 017-0083-00. 

8. 10X sampling probe. Tektronix P6034 or equivalent. 

9. 1 X probe. Tektronix P6028 or equivalent. 

10. Cable. 5 ns RG-8A/U cable with GR connectors. 
Tektronix Part No. 017-0502-00. 

11. Two cables. Impedance 50 ohm ; type RG-58A/U; 
length, 42 inches, connectors BNC. Tektronix Part No. 012- 
0057-00. 

12. Earphone. Impedance 600 ohm or higher. 



PREFORMANCE CHECK PROCEDURE 
General 

In the following procedure, test equipment connections 
or control settings should not be changed except as noted. 
If only a partial check is desired, refer to the preceding 
step(s) for setup information. 

The following procedure uses the equipment listed under 
Equipment Required. If substitute equipment is used, con- 
trol settings or setup must be altered to meet the require- 
ments of the equipment used. 

Preliminary Procedure 

1. Connect the autotransformer to a suitable power source. 

2. Connect a power cord from the Type 191 to the auto- 
transformer output. 

3. Set the autotransformer to 115 (or 230) volts. 

4. Set the Type 191 POWER switch to ON. Allow at 
least 5 minutes warm up for checking the instrument to the 
given accuracies. 



Control Settings 

ON 
.5-5 V 
5 

CAL 

50 kHz ONLY 

Set to .5 mark of .35 — .75 
scale 

Set for correct line 
voltage 

1. Check Amplitude Switch 

a. Requirement — The output signal amplitude should be 
within d=3% (.5-5 V range is used) of the front panel indi- 
cated output. 

b. Connect a 1 volt square wave signal from the standard 
amplitude calibrator through a 50 ohm coaxial cable to the 
vertical input of the test oscilloscope. 



POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Amplitude) 
FREQUENCY RANGE 
Frequency (dial) 

1 15 V/230 V (rear panel) 




Performonce Check — Type 191 



c. Set the test oscilloscope controls as follows: 



Vertical Input Coupling 


AC 


Volts/Div 


.2 


Trigger Mode 


Automatic 


Trigger Slope 


-f 


Trigger Source 


Internal 


Time/Div 


1 ms 



d. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

e. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

f. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a 50 
ohm GR to BNC termination to the vertical input connector 
on the test oscilloscope. 

g. Set the Time/Div switch on the test oscilloscope to 
20 fis. 

h. Check — For a test oscilloscope display whose ampli- 
tude is 2.5 divisions (0.5 volt) d=3%. 

i. Set the Type 191 AMPLITUDE switch to 10. 

j. Check for a test oscilloscope display whose amplitude 
is 5 divisions (1 volt) d=3%. 

k. Disconnect the Type 191. 

l. Connect a 2 volt square-wave signal from the standard 
amplitude calibrator through a 50 ohm coaxial cable to the 
vertical input of the test oscilloscope. 

m. Set the Volts/ Div control of the test oscilloscope to 
0.5. 

n. Adjust the vertical gain of the test oscilloscope to 
obtain exactly four divisions of vertical display. 

o. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

p. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the vertical input connector 
on the test oscilloscope. 

q. Set the Type 191 AMPLITUDE switch to 15. 

r. Check for a test oscilloscope display whose amplitude 
is 3 divisions (1.5 volts) ±3%. 

s. Set the Type 191 AMPLITUDE switch to 20. 

t. Check for a test oscilloscope display whose amplitude 
is 4 divisions (2 volts) ±3%. 

u. Set the Type 191 AMPLITUDE switch to 25. 

v. Check for a test oscillloscope display whose amplitude 
is 5 divisions (2.5 volts) zt3%. 

w. Disconnect the Type 191. 

x. Connect a 5 volt square-wave signal from the standard 
amplitude calibrator through a 50 ohm coaxial cable to the 
vertical input of the test oscilloscope. 



y. Set the Volts/Div control of the test oscilloscope to 1. 

z. Adjust the vertical gain of the test oscilloscope to 
to obtain exactly five divisions of vertical display. 

aa. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

ab. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the vertical input connector on 
the test oscilloscope. 

ac. Set the Type 191 AMPLITUDE switch to 30. 

ad. Check for a test oscilloscope display whose amplitude 
is 3 divisions (3 volts) ±3%. 

ae. Set the Type 191 AMPLITUDE switch to 35. 

af. Check for a test oscilloscope display whose amplitude 
is 3.5 divisions (3.5 volts) ±3%. 

ag. Set the Type 191 AMPLITUDE switch to 40. 

ah. Check for a test oscilloscope display whose amplitude 
is 4 divisions (4 volts) ±3%. 

ai. Set the Type 191 AMPLITUDE switch to 45. 

aj. Check for a test oscilloscope display whose amplitude 
is 4.5 divisions (4.5 volts) ±3%. 

ak. Set the Type 191 AMPLITUDE switch to 50. 

al. Check for a test oscilloscope display whose amplitude 
is 5 divisions (5 volts) ±3%. 

2. Check Amplitude Variable Control 

■a. Requirement — Must increase the amplitude of the out- 
put signal from its indicated value to that of the next higher 
control setting. When the AMPLITUDE switch is set to 50, the 
VARIABLE control must increase output amplitude to approxi- 
mately 10% above calibrated value. The signal should 
smoothly increase in amplitude as the VARIABLE (Amplitude) 
control is rotated clockwise. 

b. Again check for a test oscilloscope display of 5 divi- 
sions. 

c. Slowly rotate the VARIABLE (Amplitude) control clock- 
wise from its CAL position. 

d. Check for a smooth increase in output signal amplitude 
and for a test oscilloscope display of about 5.5 divisions 
when the VARIABLE (Amplitude) control is fully clockwise. 

e. Return the VARIABLE (Amplitude) control to its CAL 
position. 

f. Disconnect the Type 191 from the test oscilloscope. 

3. Check Amplitude Range Switch 

a. Requirement — Output signals for the 0.5-5 V range 
must be within ±3% of the indicated amplitude. Output 
signals for the 50-500 mV range must be within ±4% of 
the indicated amplitude. Output signals for the 5-50 mV 
range must be within ±5% of the indicated amplitude. 



® 



5-2 




Performance Check — Type 191 



b. Connect a 5 volt square-wave signal from the standard 
amplitude calibrator through a 50 ohm coaxial cable to the 
vertical input of the test oscilloscope. 

c. Set the test oscilloscope Volts/Div control to 1 volt. 

d. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

e. Disconnect the standard amplitude calibrator from the 
test oscilloscope. 

f. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the vertical input connector 
on the test oscilloscope. 

g. Check for a test oscilloscope display whose amplitude 
is 5 divisions (5 volts) d=3%. 

h. Disconnect the Type 191 from the test oscilloscope. 

i. Connect a 0.5 volt square-wave signal from the stand- 
ard amplitude calibrator through a 50 ohm coaxial cable 
to the vertical input of the test oscilloscope. 

j. Set the test oscilloscope Volts/Div control to 0.1 volt. 

k. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

l. Disconnect the standard amplitude calibrator from the 
test oscilloscope. 

m. Connect *the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a GR 
to BNC 50 ohm termination to the vertical input connector 
on the test oscilloscope. 

n. Set the Type 191 AMPLITUDE RANGE switch to 50- 
500 mV. 

o. Check for a test oscilloscope display whose amplitude 
is 5 divisions ± 4 %. 

p. Disconnect the Type 191 from the test oscilloscope. 

q. Connect a 0.05 volt square-wave signal from the stand- 
ard amplitude calibrator to the vertical input of the test 
oscilloscope. 

r. Set the test oscilloscope Volts/Div control to 0.01 volt. 

s. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

t. Disconnect the standard amplitude calibrator from the 
test oscilloscope. 

u. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the vertical input connector 
on the test oscilloscope. 

v. Set the Type 191 AMPLITUDE RANGE switch to 5- 
50 mV. 

w. Check for a test oscilloscope display whose amplitude 
is 5 divisions ±5%. 

x. Disconnect the Type 191 from the test oscilloscope. 

4. Check Frequency Ranges’ Linearity and 
Accuracy 

a. Requirement — Output signal frequency should be within 
2% of the indicated frequency for all signal amplitudes 
when the Type 191 is properly terminated into 50 ohms. 



b. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the Channel 1 vertical input 
connector on the test oscilloscope. 

c. Connect a 20 ns signal from the Time-Mark Generator 
Marker Output connector through a 50 ohm coaxial cable 
to the Channel 2 vertical input connector on the test oscillo- 
scope. 

d. It is necessary to set only the following test oscillo- 
scope controls: 

Channels 1 and 2 
Vertical Input Coupling AC 

Volts/Div .05 

Vertical Channel Mode Add 

e. Set the Type 191 AMPLITUDE RANGE switch to 50- 
500 mV. 

f. Connect the signal lead from the earphone to the 
Vert Sig Out connector of the test oscilloscope. 

g. Connect the shield lead from the earphone to a ground 
connector on the test oscilloscope. 

h. Using Table 5-1 as a guide, set up the Type 191 and 
the time-mark generator controls as described for each 
frequency setting of the Type 191. 

i. Check for a zero beat frequency close to the frequency 
points indicated in Table 5-1. The zero beat frequency is 
the null point where no tone can be heard between two 
audible tones. 



TABLE 5-1 



Type 


191 


Time-Mark Generator 
Time Markers 
or Sine Waves 


Frequency 

(dial) 


FREQUENCY 
RANGE Switch 


50 MHz 


42-100 


20 ns 


60 MHz 


42-100 


20 ns 


80 MHz 


42-100 


50 ns 


100 MHz 


42-100 


20 ns 


20 MHz 


18-42 


50 ns 


30 MHz 


18-42 


50 ns 


40 MHz 


18-42 


50 ns 


8 MHz 


8-18 


1 /AS 


13 MHz 


8-18 


1 /AS 


18 MHz 


8-18 


1 /AS 


4 MHz 


3.6-8 


1 /AS 


6 MHz 


3.6-8 


1 /AS 


8 MHz 


3.6-8 


1 /AS 


1 .6 MHz 


1.6-3. 6 


5 /as 


2.6 MHz 


1 .6-3.6 


5 /AS 


3.6 MHz 


1 .6-3.6 


5 /as 


.75 MHz 


.75-1.6 


1 0 /AS 


1.1 MHz 


.75-1.6 


1 0 /AS 


1 .6 MHz 


.75-1.6 


5 /AS 


.35 MHz 


.35-75 


1 0 /AS 


.5 MHz 


.35-75 


10 /AS 


.75 MHz 


.35-75 


10 /AS 


.5 MHz 


50 kHz ONLY 


1 0 /AS 




Performance Check — Type 191 



j. Disconnect Type 191, Time-Mark Generator and the 
earphones from the test oscilloscope. 



5. Check Output Amplitude Regulation 

a. Requirement — See Table 5-2. 

b. Set the Type 191 AMPLITUDE switch to 5 and the 
AMPLITUDE RANGE switch to .5-5 V. 

c. To the OUTPUT connector of the Type 191, connect a 
VP-1 voltage pickoff unit, a 5 ns length of RG-8A/U coaxial 
cable, a VP-2 voltage pickoff unit, and a 50 ohm BNC to 
GR termination. 

d. Connect a 1 X probe (furnished with the Type 4S3 vert- 
ical plug-in) from the vertical probe input connector to the 
appropriate connection of the VP-2 voltage pickoff unit. 

e. Connect a 10X sampling probe from the external 
trigger input connector of the test oscilloscope to the appro- 
priate connection on the VP-1 voltage pickoff unit. 

f. Set the test oscilloscope controls as follows: 

Vertical Plug-In 



Millivolts/Div 


100 


Vertical Position 


Midrange 


DC Offset 


Midrange 


Display 


Normal 


Smoothing 


Refer to p< 
step 


Low Noise-Fast 


Low Noise 


Risetime 


Vertical Mode 


Channel A 


Horizontal Plug-In 


Samples/Div 


100 


Time Position 


Midrange 


Equivalent Time/Div 


1 0 ns 


Trig Level 


Midrange 


Stability 


Midrange 


Trigger Source 


External 


Trigger Slope 


+ 


External Trigger Mode 


50 Q AC 


Sweep Mode 


Normal 


Oscilloscope 


Horizontal Display 


XI 


Horizontal Position 


Midrange 



g. Adjust the smoothing control for a loop gain of one; 
see procedure in Type 4S3 Instruction Manual. The equiva- 
lent time/division and the stability control will need to be 
changed during the procedure to obtain a readable display. 

h. Set the autotransformer for an output voltage 10% 
below the nominal line voltage. 



TABLE 5-2 



Frequency Range 


Output Amplitude 
Limits 

(Peak to Peak) 


1 Maximum 

Amplitude 

Variation 


.35 MHz to 42 MHz 


5 mV to 5.5 V 


±3% 


42 MHz to 100 MHz 


50 mV to 5.5 V 


±3% 


42 MHz to 100 MHz 


5 mV to 55 mV 


+3% 






and 






-5% 



Amplitude variation is referenced to actual amplitude at 50 kHz. 



i. Adjust the vertical plug-in Variable control to obtain 
a test oscilloscope vertical display of 7.8 divisions. 

j. Change the FREQUENCY RANGE switch to .35 .75 
and rotate the Frequency (dial) from one extreme to the 
other. Repeat this procedure until the complete frequency 
range from .35 MHz to 100 MHz has been checked. 

k. Check — That as Step j is accomplished the Type 191 
output amplitude does not vary more than the amount 
shown in Table 5-2 and that the waveform has minimum 
distortion. 

l. Change the Type 191 AMPLITUDE RANGE switch to 
50-500 mV and the FREQUENCY RANGE switch to 50 kHz 
ONLY. 

m. Set the Type 191 AMPLITUDE switch to 50 and rotate 
the VARIABLE (Amplitude) fully clockwise. 

n. Adjust the vertical plug-in Variable control to obtain 
a test oscilloscope vertical display of 7.8 divisions. 

o. Change the FREQUENCY RANGE switch to .35-75 
and rotate the Frequency (dial) from one extreme to the 
other. Repeat this procedure until the complete frequency 
range from .35 MHz to 100 MHz has been checked. 

p. Check — That as part o is accomplished, the Type 191 
output amplitude does not vary more than the amount 
shown in Table 5-2. 

q. Change the Type 191 AMPLITUDE RANGE switch to 
5-50 mV, and the FREQUENCY RANGE switch to 50 kHz 
ONLY. 

r. Set the test oscilloscope millivolts/division control to 
10. 

s. Adjust the vertical plug-in Variable control to obtain 
a test oscilloscope vertical display of 7.8 divisions. 

t. Change the FREQUENCY RANGE switch to .35-75 and 
rotate the Frequency (dial) from one extreme to the other. 
Repeat this procedure until the complete frequency range 
from ,35 MHz to 100 MHz has been checked. 

u. Check — That as part t is accomplished the Type 191 
output amplitude does not vary more than the amount 
shown in Table 5-2. 

v. Rotate the VARIABLE (Amplitude) control to its CAL 
position. 

w. If desired, other Type 191 output amplitudes may be 
checked. However, the three output levels which have 
been checked will provide adequate assurance that the 
output amplitude regulation is within the proper tolerance. 

This completes the performance check of the Type 191. 
Disconnect all test equipment. If the instrument has met 
all performance requirements given in this procedure, it 
is correctly calibrated and within the specified tolerances. 




SECTION 6 
CALIBRATION 



Introduction 

The Type 191 Constant Amplitude Signal Generator is 
a stable instrument which will provide many hours of 
trouble-free operation. However, to insure measurement 
accuracy, it is suggested that you recalibrate the instru- 
ment after each 500 hours of operation, or every six months 
if used intermittently. It will also be necessary to recali- 
brate certain sections of the instrument when tubes, tran- 
sistors or other components that affect the calibration 
accuracy of the instrument are replaced. 

This calibration procedure can be used either for com- 
plete calibration of the Type 191 to return it to original 
performance, or as an operational check of instrument per- 
formance. Completion of every step in this procedure 
returns the Type 191 to original factory performance stand- 
ards. If it is desired to merely touch up the calibration, 
perform only those steps entitled Adjust. 

NOTE 

The Adjust steps provide a check of instrument 
performance before the adjustment is made. To 
prevent the need for recalibration of other 
circuits when performing a partial calibration, 
readjust only if the listed tolerance is not met. 

General Information 

Any needed maintenance should be performed before 
proceeding with calibration. Troubles which become appar- 
ent during calibration should be corrected using the tech- 
niques given in the Maintenance section of the Instruction 
Manual. 

This procedure is arranged in a sequence which allows 
this instrument to be calibrated with the least interaction 
of adjustments and reconnection of equipment. If desired, 
the steps may be performed out of sequence or a step may 
be done individually. However, some adjustments affect 
the calibration of other circuits within the instrument. In 
this case, it will be necessary to check the operation of 
other parts of the instrument. When a step interacts with 
others, the steps which need to be checked will be noted. 

The location of test points and adjustments is shown in 
each step. Waveforms which are helpful in determining the 
correct adjustment or operation are also shown. 

EQUIPMENT REQUIRED 

(see Figs. 6-1 and 6-2) 

General 

The following equipment or its equivalent is required 
for complete calibration of the Type 191. Specifications 
given are the minimum necessary for accurate calibration 
of this instrument. All test equipment is assumed to be cor- 
rectly calibrated and operating within the original specifi- 



cations. If equipment is substituted, it must meet or exceed 
the specifications of the recommended equipment. 

Special Test Equipment 

For the quickest and most accurate calibration, special 
calibration fixtures are used where necessary. All calibra- 
tion fixtures listed under Equipment Required can be 
obtained from Tektronix, Inc. Order by part number through 
your local Tektronix Field Office or representative. 

1. DC voltmeter. Minimum sensitivity, 20,000 ohms/volt; 
accuracy, checked to within 1% at 6.2 and 11 volts, and 
checked to within 3% at 450 volts. For example, Simpson 
Model 262. 

2. Real-time test oscilloscope. Bandpass, DC to 10 MHz; 
minimum deflection factor, 0.005 volts/division. Tektronix 
Type 547 Oscilloscope with Type 1A1 plug-in unit or equiv- 
alent. 

3. Sampling test oscilloscope. Bandwidth, equivalent to 
DC to 1000 MHz; minimum deflection factor, 5 millivolts/ 
division. Tektronix Type 661 Oscilloscope with a Type 4S3 
vertical plug-in and a Type 5T3 timing plug-in. 

4. Standard amplitude calibrator. Amplitude accuracy, 
within ±0.25%; signal amplitude, 0.01 volts to 2 volts; 
output frequency, 1 kHz. Tektronix calibration fixture 067- 
0502-00 or equivalent. 

5. Time-mark generator. Marker output of 1 /as, 5 /as and 
10 /as; sine wave outputs of 20 ns and 50 ns; accuracy, 
0.001%. Tektronix Type 184 or equivalent. 

6. Variable autotransformer. Must be capable of sup- 
plying at least 25 watts to the Type 191 over a voltage 
range of 94 to 138 volts (188 to 276 volts for 230-volt nom- 
inal line). If autotransformer does not have an AC volt- 
meter to indicate output voltage, monitor output with an 
AC voltmeter (rms) with range of at least 138 (or 276) volts. 
For example, General Radio W10MT3W Metered Variac 
Autotransformer. 

7. Precision DC voltmeter. Accuracy, within d=0.05%; 
meter resolution, 50 / aV; range, 11 volts. For example. Fluke 
Model 801 B. 

8. 50 ohm voltage pickoff unit. Tektronix VP-2 or equiv- 
alent. 

9. Termination. Impedance 50 ohms; accuracy, dtl %; 
connectors, BNC jack to GR. Tektronix Part No. 017- 
0083-00. 

10. 100X sampling probe. Tektronix P6035 or equiva- 
lent. 

11. IX probe. Tektronix P6028 or equivalent. 

12. Cable. 5 ns RG-8A/U cable with GR connectors. 
Tektronix Part No. 017-0502-00. 

13. Two cables. Impedance 50 ohms; type RG-58A/U: 
length, 42 inches, connectors, BNC. Tektronix Part No. 
012-0057-00. 



® 



6-1 





Fig. 6-1. lUcommondod calibration •quipmont. Itomt 1 through 12. 







Calibration — Type 191 





(16) 



lb) 



Id) 



Fig 6*7 R»comm#nd«d calibration oqvipmont. Ilvmi 17 through 16 



14. Adapter. Connectors, BNC plug to GR. Tektronix 
Part No. 017-0064-00. 

15. Earphone. Impedance 600 ohms or higher. 

16. Adjustment tools. 


Description 


Tektronix 
Part No. 


o. Insulated screwdriver l 1 /* inch shaft, 


003-0000 00 


non-metallic 




b. Nutdriver with V 4 inch socket, overall 
length 6 inches 


003-0132-00 


c. Tuning tool: 




Handle 


003-0307-00 


Insert, for 5 /*4 inch ID hex cores 


003-0310-00 


d. Tuning Tool: 

Rod, 7 inches long with recessed 
metal screwdrive tips 


003 0003 00 



CALIBRATION RECORD AND INDEX 

This Abridged Calibration Procedure is provided to aid 
in checking the operation of the Type 191. It may be used 
as a calibration guide by the experienced calibrator, or it 
may be used as a calibration record. Since the step num- 
bers and titles used here correspond to those used in the 



complete Calibration Procedure, tho following short form 
list moy serve as an index. Characteristics are thoso listed 
in the Calibration Procedure of the Instruction Manual. 

Type 191, Serial No. 

Calibration Date 

□ 1. Adjust —11 Volt Power Supply, Page 6-6. 

Adjust to —11 volts. 

□ 2 Check 4*6.2 Volt Power Supply. Page 6-6. 

Check for 4-6 2 volts. 

□ 3. Check 4 450 Volt Unregulated Power Supply. Page 

6-7. 

Check for about 4 450 volts. 

□ 4. Check —11 Volt and 4*6.2 Volt Power Supply 

Ripple Page 6-8. 

About 4 mV of ripple allowable on each power 
supply voltage. 

□ 5. Adjust —11 Volt Power Supply. Page 6-9. 

Adjust for exactly 10 volts of untermmated sine 
wave output. 

□ 6. Adfust Amplitude Tracking Page 6-11. 

Adjust for 1 volt rtr5 mV across the VARIABLE 
(Amplitude) control. 



Calibration — Type 191 



□ 7. Adjust Amplitude Calibration. Page 6-12. 

Adjust for exactly 1 volt of unterminated sine 
wave output. 

□ 8. Check Amplitude Variable Control. Page 6-12. 

Full clockwise rotation should increase AMPLI- 
TUDE switch setting output amplitude to the 
next fixed output amplitude of the AMPLITUDE 
switch, or if the AMPLITUDE switch is set to 50 
it will increase the output amplitude by 10%. 

□ 9. Check Amplitude Range Switch. Page 6-13. 

.5-5 V ±3% 

50-500 mV ±4% 

5-50 mV ±5% 

□ 10. Adjust Frequency Ranges. Page 6-15. 

Adjust each frequency range for a zero beat 
at the indicated frequencies. 



TABLE 6-1 



Type 191 


Time-Mark 
Generator 
Time 
Markers 
or Sine 
Waves 


Type 191 
Adjustment 


Frequency 

(dial) 


Frequency 

RANGE 

switch 


50 MHz 


42-100 


20 ns 


T38 


100 MHz 


42-100 


20 ns 


C38 


20 MHz 


18-42 


50 ns 


T34 


40 MHz 


18-42 


50 ns 


C34 


8 MHz 


8-18 


1 (IS 


T30 


18 MHz 


8-18 


1 (IS 


C30 


4 MHz 


3.6-8 


1 (IS 


T26 


8 MHz 


3.6-8 


1 /AS 


C26 


1 .6 MHz 


1 .6-3.6 


5 /as 


T22 


3.6 MHz 


1 .6-3.6 


5 /as 


C22 


.75 MHz 


.75-1 .6 


10 /AS 


T18 


1 .6 MHz 


.75-1 .6 


5 /as 


Cl 8 


.35 MHz 


.35-75 


1 0 (is 


T14 


.75 MHz 


.35-75 


1 0 (is 


C14 


.5 MHz 


50 kHz 
ONLY 


5 /as 


T10 



Q 11. Check Frequency Ranges Accuracy. Page 6-16. 

Check each frequency range for a zero beat 
at the indicated frequencies. 



TABLE 6-2 



Type 


191 


Time-Mark 
Generator 
Time Markers 
or Sine Waves 


Frequency 
(dial ) 


FREQUENCY 
RANGE switch 


50 MHz 


42-100 


20 ns 


60 MHz 


42-100 


20 ns 


80 MHz 


42-100 


50 ns 


100 MHz 


42-100 


20 ns 


20 MHz 


18-42 


50 ns 


30 MHz 


18-42 


50 ns 


40 MHz 


18-42 


50 ns 


8 MHz 


8-18 


1 (IS 


13 MHz 


8-18 


1 /AS 


18 MHz 


8-18 


1 /AS 


4 MHz 


3.6-8 


1 /AS 


6 MHz 


3.6-8 


1 /AS 


8 MHz 


3.6-8 


1 /AS 


1.6 MHz 


1. 6-3.6 


5 /as 


2.6 MHz 


1. 6-3.6 


5 / as 


3.6 MHz 


1. 6-3.6 


5 (is 


.75 MHz 


75-1 .6 


10 /as 


1.1 MHz 


.75-1 .6 


1 0 (is 


1.6 MHz 


.75-1 .6 


5 /as 


.35 MHz 


.35-75 


1 0 (is 


.5 MHz | 


.35-75 


1 0 /as 


75 MHz | 


.35-75 


1 0 /AS 



TABLE 6-3 



Frequency Range 


Output 

Amplitude 

Limits 

(peak to peak) 


x Maximum 

Amplitude 

Variation 


.35 MHz to 42 MHz 


5 mV to 5.5 V 


±3% 


42 MHz to 100 MHz 


50 mV to 5.5 V 


±3% 


42 MHz to 100 MHz 


5 mV to 55 mV 


-f-3% and —5% 



Amplitude variation is referenced to actual amplitude at 50 kHz. 



□ 12. Check Output Amplitude Regulation. Page 6-17. 

Check the output signal amplitude for the re- 
quired tolerance over the indicated frequency 
range. 



NOTES 



6-4 



®\ 




Calibration — Type 191 



General 

In the following calibration procedure, a test equipment 
setup is shown for each major setup change. Complete 
control settings are listed below the picture. If only a par- 
tial calibration is performed, start with the nearest setup 
preceding the desired portion. 

NOTE 

When performing a complete recalibration, best 
performance will be provided if each adjustment 
is made to the exact setting, even if the Check is 
within the allowable tolerance. 

The following procedure uses the equipment listed under 
Equipment Required. If substitute equipment is used, con- 
trol settings or setup must be altered to meet the require- 
ments of the equipment used. 

Preliminary Procedure 

1. Remove the Type 191 from its case to allow access 
to all internal adjustments and test points. 



2. Rotate the Frequency (dial) clockwise until the plates 
of capacitor CIO just become fully meshed. Check that the 
Frequency (dial) now indicates a frequency of 42 MHz (on 
the 42-1 00 MHz scale); if it does not, loosen the two 
screws holding the Frequency (dial) mechanism to the shaft 
of capacitor CIO, then rotate the Frequency (dial) so it 
indicates a frequency of 42 MHz (on the 42-1 00 MHz scale) 
and retighten the two screws. 

3. Connect the autotransformer (if used) to a suitable 
power source. 

4. Connect a power cord from the Type 191 to the auto- 
transformer output (or directly to the power source). 

5. Set the autotransformer to 115 (or 230) volts. 

6 . Set the Type 191 POWER switch to ON. Allow at 
least 5 minutes warm up for checking the instrument to 
the given accuracies. 



NOTES 




Calibration— Type 191 




Fig. 6-3. T«bI equipment tetup for itept 1 through 3. 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Amplitude) 
FREQUENCY RANGE 
Frequency (dial) 

115 V/230 V (rear panel) 



ON 
.5*5 V 
50 
CAL 

50 kHz ONLY 
Set to .5 mark of .35*75 
scale 

Set for correct line volt* 
age. 



e. Adjust —11 VOLTS control, R122 (see Fig. 6*4) until 
about a —11 volt reading is obtained on the DC voltmeter. 

f. Set the autotransformer output voltage 10% above 
the nominal line voltago and check that the DC voltmeter 
still reads about —11 volts. 

g. Set the autotransformer output voltage 10% below 
the nominal line voltage and check that the DC voltmeter 
still reads about —11 volts. 

h. Interaction-May affect all circuits. 

i. Disconnect the DC voltmeter and return the auto- 
transformer output voltage to nominal line voltage. 



1. Adjust —11 -Volt Power Supply O 

a. Test equipment setup is shown in Fig. 6-3. 

d. Connect the negative lead of the DC voltmeter to 
the junction of R122, R123 and Cl 28; see Fig. 6 4. 

c. Connect the positive DC voltmeter lead to ground. 

d. Check — For about a —11 volt reading on the DC 
voltmeter. 



2, Check + 6.2-Volt Power Supply 

a. Test equipment setup is shown in Fig. 6-3. 

b. Connect the positive lead of the DC voltmeter to the 
junction of Dll 7 and Cl 27; see Fig. 6-4. 

c. Connect the negative lead of the DC voltmeter to 
ground. 

d. Check — For a DC voltmeter reading of about 6.2 volts. 



® 



6-6 






Calibration — Type 191 




Fig. 6*4. location ot 111 17, 1193 and Cl 31 function, —11 VOLTS 
control, and tho function of Dll 7 and Cl 37. 

g. Interaction— May affect operation of Feedback DC 
Amplifier and -11-Volt Power Supply. 

f. Disconnect DC voltmeter. 

3. Check + 450-Volt Unregulated Power Supply 

a. Test equipment setup is shown in Fig. 6*3. 

b. Connect the positive lead of the DC voltmeter to the 




Fig 6-9. location of C137A and K140 function. 



junction of C132A and R 1 40; see Fig. 6-5. 

c. Connect the negative DC voltmeter load to ground. 

d. Check — For a DC voltmeter reading between 435 volts 
and 450 volts. 

e. Interaction — May affect operation of Oscillator circuit. 

f. Disconnect DC voltmeter. 



NOTES 






6-7 




Calibration— Type 191 




Fig. 6-6. T««t equipment »«tup for Atop 4. 



Control Settings 



d. Check* For about 4 mV of ripple. 



POWER 


ON 


AMPLITUDE RANGE 


.5-5 V 


AMPLITUDE 


50 


VARIABLE (Amplitude) 


CAL 


FREQUENCY RANGE 


50 kHz ONLY 


Frequency (dial) 


Set to .5 mark of .35-75 
scale 


115V/230V (rear panel) 


Set for correct line volt- 




age 


4. Check — 11 -Volt and + 6.2-Volt Power 


Supply Ripple 




a. Test equipment setup is shown in Fig. 6-6. 


b. Connect a 1 X probe from the test oscilloscope to 
tho junction of R122, R123 and Cl 28; see Fig. 6-4. 


c. Set the test oscilloscope 


controls as follows: 


Vertical Input Coupling 


AC 


Volts/Div 


.005 


Trigger Mode 


Automatic 


Trigger Slope 


+ 


Trigger Source 


Line 


Time/Div 


5 ms 



e. Set the autotransformer output voltage 10% above 

the nominal line voltage. 

f. Check— -For about 4 mV of ripple. 

g. Set the autotransformer output voltage 10% below 

tho nominal line voltago. 

h. Chock — For about 4 mV of ripple. 

i. Return the autotransformer output voltage to the nom- 
inal line voltage. 

j. Change the 1 X probe connection to the junction of 
D1 1 7 and C 1 27; see Fig. 6-4. 

k. Check — For about 4 mV of ripple. 

l. Set the autotransformer output voltage 10% above 

the nominal line voltage. 

m. Check— For about 4 mV of ripple. 

n. Set the autotransformer output voltage 10% below the 
nominal line voltage. 

o. Check for about 4 mV of ripple. 

p. Disconnect the 1 X probe and return the autotrans- 
former output voltage to the nominal line voltage. 






6-8 






Calibration — Typo 191 




Adopter 



Fig. 6-7. T#«t •qulpm«nt »«tup Ur tfep 5. 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 

VARIABLE (AMPLITUDE) 
FREQUENCY RANGE 
Frequency (dial) 

1 15 V/230 V (rear panel) 



ON 
.5-5 V 
50 
CAL 

50 kHz ONLY 
Set to .5 mark of .35*75 
scale 

Set for correct line volt* 
age 



5. Adjust -11-Volt Power Supply O 

a. Test equipment setup is shown in Fig. 6-7. 

b. Connect a 10 volt square-wave signal from the stand- 
ard amplitude calibrator to the vertical input of the test 
oscilloscope. 

c. Set the test oscilloscope controls as follows: 

Vertical Input Coupling AC 

Volts/Div 2 



Trigger Mode Automatic 

Trigger Slope + 

Trigger Source Internal 

Time/Div 1 ms 

d. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

e. Disconnect the standard amplitude calibrator from 
the test oscilloscopo. 

f. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC adapter to the vertical input connector on the test 
oscilloscope; see Fig. 6-8. 

g. Set the Time/Div switch on the test oscilloscope to 
0.2 ms. 

h. Check— For a test oscilloscope display whose ampli- 
tude is exactly 5 divisions (10 volts). 

i. Adjust the —11 VOLTS control (see Fig. 6-4) to 
obtain a test oscilloscope display of exactly 5 divisions. 

j. Interaction— Interacts with steps 6 and 7. 

k. Disconnect the Type 191 from the test oscilloscope 





Calibrator*— Type 191 







Fig. 6*1. Type 191 connection to root time totf otcillotcope 

NOTES 






6-10 






Calibration — Type 191 




Fig 6-9. Tilt equipment telup for *lop 6. 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Amplitude) 
FREQUENCY RANGE 
Frequency (dial) 

1 15 V/230 V (reor panel) 



ON 
.5-5 V 
50 
CAL 

50 kHz ONLY 
Set to .5 mark ol .35-75 
scale 

Set (or correct lino volt- 
age 



6. Adjust Amplitude Tracking O 

o. Test equipment setup is shown in Fig. 6-9. 

b. Connect the negative lead of a precision DC volt- 
meter to the — 11 volt end of R53L; see Fig. 6-10. 

c. Connect the positive lead of the precision DC volt- 
meter to the junction of R53J and R53K; see Fig. 6-10. 

d. Check — For a voltage of 1 volt i:5mV. 

e. Adjust TRACKING control, R55 (see Fig. 6-12) to 
obtain a voltage 1 volt ±5 mV. 




Fig. 6-10. locotion ol —11 volt ond of *531 ond tho junction 
ol RS3J and R53K. 

f. Interaction — Interacts with steps 5 ond 7. 

g. Disconnect the precision DC voltmeter. 






6-11 






Calibration — Type 191 




Fig. 6-11. oquipmont »#fup for ittpt 7 and 9 . 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Amplitude) 
FREQUENCY RANGE 
Frequency (dial) 

1 15 V/230 V (rear panel) 



ON 
.5-5 V 
5 

CAL 

50 kHz ONLY 
Set to .5 mark of .35-75 
scale 

Set for correct line volt. 

age 



7. Adjust Amplitude Calibration O 

a. Test equipment setup is shown in Fig. 6-11. 

b. Connect a 1 volt square-wave signal from the stand- 
ard amplitude calibrator to the vertical input of the test 
oscilloscope. 



d. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

e. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

f. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a GR 
to BNC adapter to the vertical input connector on the test 
oscilloscope; see Fig. 6-8. 

g. Set the Time/Div switch on the test oscilloscope to 
0.2 ms. 

h. Check — For a test oscilloscope display whose ampli- 
tude is exactly 5 divisions (1 volt). 

i. Adjust the AMPL CAL control (see Fig. 6-12) to obtain 
a test oscilloscope display of exactly 5 divisions. 

j. Interaction — Interacts with steps 5 and 6. 



c. Set the test oscilloscope controls as follows: 



8. Check Amplitude Variable Control 



Vertical Input Coupling 


AC 


a. Test equipment setup is given in step 7. 


Volts/Div 


.2 


b. Set the Type 191 AMPLITUDE switch to 50. 


Trigger Mode 


Automatic 


Trigger Slope 


+ 


c. Set the test oscilloscope Volts/Div control to 2 volts. 


Trigger Source 


Internal 


d. Check — For a test oscilloscope display amplitude of 


Time/Div 


1 ms 


about 5 divisions. 





Calibration — Type 191 




Fl«. 6-12. Location of TRACKING and AMPl CAL contral*. 



e Slowly rotate the VARIABLE (Amplitude) control clock- 
wise and check for a smoothly increasing signal display 
on the test oscilloscope. 

f. Check— For a test oscilloscope display amplitude of 
about 5.5 divisions with the Type 191 VARIABLE (Ampli- 
tude) control fully clockwise. 

g. Rotate the Type 191 VARIABLE (Amplitude) control 
to its CAL position. 

h. Disconnect the Type 191 from the test oscilloscope. 



9. Check Amplitude Range Switch 

a. Te»t equipment setup is shown in Fig. 6-11. 

b. Connect a 5 volt square-wave signal from the stand- 
ard amplitude calibrator to the vertical input of the test 
oscilloscope. 

c. Set the test oscilloscope Volts/Div control to 1 volt. 

d. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 



e. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

f. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a 
GR to BNC 50 ohm termination to the vertical input con- 
nector on the test oscilloscope; see Fig. 6-13. 

g. Check— For a test oscilloscope display whose ampli- 
tude is 5 divisions (5 volts) db3%. 

h. Disconnect the Type 191 from the test oscilloscope. 

i. Connect a 0.5 volt square-wave signal from the stand- 
ard amplitude calibrator to the vertical input of the test 
oscilloscope. 

j. Set the test oscilloscope Volts/Div control to 0.1 volt. 

k. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

l. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

m. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a 
GR to BNC 50 ohm termination to the vertical input con- 
nector on the test oscilloscope; see Fig. 6-13. 

n. Set the Type 191 AMPLITUDE RANGE switch to 
50-500 mV. 

o. Check — For a test oscilloscope display whose ampli- 
tude is 5 divisions ±:4%. 

p. Disconnect the Type 191 from the test oscilloscope. 

q. Connect a 0.05 volt square-wave signal from the 
standard amplitude calibrator to the vertical input of the 
test oscilloscope. 

r. Set the test oscilloscope Volts/Div control to 0.01 volt. 

s. Adjust the vertical gain of the test oscilloscope to 
obtain exactly five divisions of vertical display. 

t. Disconnect the standard amplitude calibrator from 
the test oscilloscope. 

u. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a 
GR to BNC 50 ohm termination to the vertical input con- 
nector on the test oscilloscope; see Fig. 6-13. 

v. Set the Type 191 AMPLITUDE RANGE switch to 
5-50 mV. 

w. Check — For a test oscilloscope display whose ampli- 
tude is 5 divisions db5%. 

x. Disconnect the Type 191 from the test oscilloscope. 





Calibration — Type 191 




Fig. 6-19. Type 191 connection to root time teet otcillotcope. 



NOTES 






Calibration — Type 191 




Fig. 6-14. ?•»» •quipm«nt »#»up for «t«pt 10 and 11. 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Amplitude) 
FREQUENCY RANGE 
Frequency (dial) 

115 V/230V (rear panel) 



ON 

50-500 mV 

50 

CAL 

42-1 00 MHz 
Set to 50 

Set for correct line volt- 
age 



10. Adjust Frequency Ranges O 

a. Test equipment setup is shown in Fig. 6-14. 

b. Loosen the lock nut on each oscillator coil. 

c. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable, and a 
GR to BNC 50 ohm termination to the channel 1 verti- 
cal input connector on the test oscilloscope. 

d. Connect a 20 ns signal from the Time-Mark Generator 
Marker Output connector through a 50 ohm coaxial cable 
to the channel 2 vertical input connector on the test oscil- 
loscope. 



e. It is necessary to set only the following test oscillo- 
scope controls. 

Channels 1 and 2 
Vertical Input Coupling AC 

Volts/Div .05 

Vertical Channel Mode Add 

f. Connect the signal lead from the earphone to the 
Vort Sig Out connector of the test oscilloscope. 

g. Connect the shield lead from the earphone to a ground 
connector on the test oscilloscope. 

h. Using Table 6-1 as a guide, set up the Type 191 and 

the time-mark generator controls as described for each 

end of each frequency setting of the Type 191. 

i. Check— For a zero beat frequency at the frequency 
points indicated in Table 6-1. The zero beat frequency 
is the point where no tone is audible between two audible 
tones. 

j. Adjust the oscillator coil (for the low end of each 
frequency range) or the trimmer capacitor (for the upper 
end of each frequency range) for a zero beat frequency. 

k. Interaction— Trimmer capacitor and oscillator coil 
adjustments for each frequency range interact with each 
other. 



6 - 1 5 






Calibration — Type 191 



TABLE 6-1 



Type 


191 


Time-Mark Generator 
Time Markers 
or Sine Waves 


Type 191 
Adjustment 


Frequency (dial) 


Frequency 
RANGE Switch 


50 MHz 


42-100 


20 ns 


T38 


100 MHz 


42-100 


20 ns 


C38 


20 MHz 


18-42 


50 ns 


T34 


40 MHz 


18-42 


50 ns 


C34 


8 MHz 


8-18 


1 /AS 


T30 


18 MHz 


8-18 


1 /AS 


C30 


4 MHz 


3.6-8 


1 /AS 


T26 


8 MHz 


3.6-8 


1 /AS 


C26 


1 .6 MHz 


1 .6-3.6 


5 /AS 


T22 


3.6 MHz 


1 .6-3.6 


5 /as 


C22 


.75 MHz 


.75-1.6 


1 0 /AS 


T18 


1.6 MHz 


.75-1.6 


5 /AS 


C18 


.35 MHz 


.35-75 


10 /AS 


T14 


.75 MHz 


.35-75 


1 0 /AS 


C14 


.5 MHz 


50 kHz ONLY 


5 /as 


T10 



1 1 . Check Frequency Ranges Accuracy 

a. Test equipment setup is shown in Fig. 6-14. 

b. Install Type 191 into its case. 

c. Connect the OUTPUT connector on the Type 191 
through a 5 ns length of RG-8A/U coaxial cable and a GR 
to BNC 50 ohm termination to the channel 1 vertical input 
connector on the test oscilloscope. 

d. Connect a 20 ns signal from the Time-Mark Generator 
Marker Output connector through a 50 ohm coaxial cable 
to the channel 2 vertical input connector on the test oscillo- 
scope. 

e. It is necessary to set only the following test oscilloscope 
controls: 

Channels 1 and 2 
Vertical Input Coupling AC 

Volts/Div .05 

Vertical Channel Mode Add 

f. Connect the signal lead from the earphone to the Vert 
Sig Out connector of the test oscilloscope. 

g. Connect the shield lead from the earphone to a ground 
connector on the test oscilloscope. 

h. Using Table 6-2 as a guide, set up the Type 191 and 
the time-mark generator controls as described for each 
frequency setting of the Type 191. 

i. Check — For a zero beat frequency close to the fre- 
quency points indicated in Table 6-2. 



TABLE 6-2 



Type 


191 


Time-Mark Generator 
Time Markers 
or Sine Waves 


Frequency 

(dial) 


FREQUENCY 
RANGE Switch 


50 MHz 


42-100 


20 ns 


60 MHz 


42-100 


20 ns 


80 MHz 


42-100 


50 ns 


100 MHz 


42-100 


20 ns 


20 MHz 


18-42 


50 ns 


30 MHz 


18-42 


50 ns 


40 MHz 


18-42 


50 ns 


8 MHz 


8-18 


1 /AS 


13 MHz 


8-18 


1 /AS 


18 MHz 


8-18 


1 /AS 


4 MHz 


3.6-8 


1 /AS 


6 MHz 


3.6-8 


1 /AS 


8 MHz 


3.6-8 


1 /AS 


1.6 MHz 


1 .6-3.6 


5 /as 


2.6 MHz 


1 .6-3.6 


5 /as 


3.6 MHz 


1 .6-3.6 


5 /as 


75 MHz 


.75-1 .6 


10 /AS 


1.1 MHz 


75-1 .6 


5 /AS 


1.6 MHz 


75-1 .6 


5 /as 


.35 MHz 


.35-75 


10/AS 


.5 MHz 


.35-75 


1 0 /AS 


75 MHz 


.35-75 


1 0 /AS 



j. Disconnect the Type 191, Time-Mark Generator and the 
earphones from the test oscilloscope. 

k. Remove the Type 191 from its case. 



6-16 





Calibration — Type 191 



Sampling _ 

T»»r Oscilloscope — * 2 * 




Termination 



Pig. 6-1 S. Tost equipment setup for step 12. 



Control Settings 

POWER 

AMPLITUDE RANGE 
AMPLITUDE 
VARIABLE (Ampliludo) 
FREQUENCY RANGE 
Frequency (dial) 
U5V/230V (rear panel) 



ON 
.5-5 V 
5 

CAL 

50 kHz ONLY 



As is 

Set for correct line 
voltage 



12. Check Output Amplitude Regulation 

a. Test equipment setup is shown in Fig. 5*15. 

b. Connect a 100X sampling probe from external trigger 
input connector of the sampling oscilloscope to the FRE- 
QUENCY RANGE switch end of the coaxial cable which 
runs from the switch to the sampling point. See Fig. 6-16. 

c. To the OUTPUT connector of the Type 191, connect a 
5 ns length of RG-8A/U coaxial cable, a voltage pickoff 
unit, and a 50 ohm BNC to GR termination. 

d. Connect a 1 X probe (furnished with the Type 4S3 verti- 
cal plug-in) from the vertical probe input connector to the 
appropriate connection on the voltage pickoff unit. 

e. Set the sampling oscilloscope controls as follows: 



Vertical Plug-In 
Millivolts/Div 
Vertical Position 
DC Offsot 
Display 
Smoothing 

Low Noise-Fast 
Risetime 
Vertical Mode 

Horizontal Plug-In 
Samplcs/Div 
Time Position 
Equivalent Time/Div 
Trig Level 
Stability 
Trigger Source 
Trigger Slope 
External Trigger Mode 
Sweep Mode 

Oscilloscope 



100 

Midrange 

Midrange 

Normal 

Refer to part f of this 
step 

Low Noise 
Channel A 

100 

Midrange 
10 ns 

Midrange 

Midrange 

External 

+ 

50 0 AC 
Normal 

XI 



Horizontal Display 
Horizontal Position Midrange 

f. Adjust the smoothing control for a loop gain of one; 
see procedure in Type 4S3 Instruction Manual. The equival- 
ent time/division and the stability control will need to be 
changed during the procedure to obtain a readable display. 






Calibration — Type 191 




Pig. 6-16. Point from which OMtornal triggorlng signal for campling 
tact oiclllotcopo It dorivod. 



TABLE 6-3 



Frequency Range 


Output Amplitude 
Limits 

(peak to peak) 


'Maximum 

Amplitude 

Variation 


35 MHz to 42 MHz 


5 mV to f< 5 V 


• 3% 


42 MHz to 100 MHz 


50 mV to 5.5 V 


* 37. 


42 MHz to 100 MHz 


5 mV to 55 mV 


+3% 

and 

-57, 



'Amplitude variation it roforoncod to octwol omplitwdo ot 50 kHt. 



g. Set the autotransformer for an output voltage 10% 
below the nominal line voltage 

h. Adjust the vertical plug-in Variable control to obtain 
a sampling oscilloscope vertical display of 7.8 divisions. 

i. Change the FREQUENCY RANGE switch to .35*75 
and rotate the Frequency (dial) from one extreme to the 
other. Repeat this procedure until the complete frequency 
range from .35 MHz to 100 MHz has been checked. 



j. Check— That as part i is accomplished the Type 191 
output amplitude does not vary more than the amount shown 
in Toble 6-3 and that the waveform has minimum distortion. 

k. Change the Type 191 AMPLITUDE RANGE switch to 50- 
500 mV and the FREQUENCY RANGE switch to 50 kHz 
ONLY. 

l. Set the Type 191 AMPLITUDE switch to 50 and rotate 
the VARIABLE (Amplitude) fully clockwise. 

m. Adjust the vertical plug-in Variable control to obtain 
a sampling oscilloscope vertical display of 7.8 divisions. 

n. Change the FREQUENCY RANGE switch to .35-75 and 
rotate the Frequency (dial) from one extreme to the other. 
Repeat this procedure until the complete frequency range 
from .35 MHz to 100 MHz has been checked. 

o. Check That as part n is accomplished the Type 191 
output amplitude does not vary more than the amount shown 
in Table 6-3. 

p. Change the Type 191 AMPLITUDE RANGE switch to 5- 
50 mV, and the FREQUENCY RANGE switch to 50 kHz. 

q. Set the sampling oscilloscope millivolts/division con- 
trol to 10. 

r. Adjust the vertical plug-in Variable control to obtain 
a sampling oscilloscope vertical display of 7.8 divisions. 

s. Change the FREQUENCY RANGE switch to .35-75 and 
rotate the Frequency (dial) from one exteremc to the 
other. Repeat this procedure until the complete frequency 
range from .35 MHz to 100 MHz has been checked. 

t. Check— That as part s is accomplished the Type 191 
output amplitude doos not vary more than the amount shown 
in Table 6-3. 

u. Rotate the VARIABLE (Amplitude) control to its CAL 
position. 

v. If desired other Type 191 output amplitudes may be 
checked. However the three output levels which havo been 
checked will provide adequate assurance that the output 
amplitude regulation is within the proper tolerance. 

This completes the calibration of the Type 191. Disconnect 
all test equipment and slide the instrument into its case. If 
the instrument has been completely calibrated to the toler- 
ances given in this procedure, it will perform to the limits 
given in the Characteristics section of the Instruction Manual 




ABBREVIATIONS AND SYMBOLS 





A or amp 


amperes 


L 


inductance 




AC or ac 


alternating current 


A 


lambda — wavelength 


- 


AF 


audio frequency 


» 


large compared with 




a 


alpha — common-base current amplification factor 


< 


less than 




AM 


amplitude modulation 


LF 


low frequency 






approximately equal to 


ig 


length or long 




B 


beta — common-emitter current amplification factor 


LV 


low voltage 


r ..... 


BHB 


binding head brass 


M 


mega or 10 6 




BHS 


binding head steel 


m 


milli or 10 -3 




BNC 


baby series “N” connector 


MS2 or meg 


megohm 




X 


by or times 


V 


micro or 10" 6 




C 


carbon 


me 


megacycle 




C 


capacitance 


met. 


metal 




cap. 


capacitor 


MHz 


megahertz 




cer 


ceramic 


mm 


millimeter 




cm 


centimeter 


ms 


millisecond 




comp 


composition 


— 


minus 





conn 


connector 


mtg hdw 


mounting hardware 






cycle 


n 


nano or 10" 9 




c/s or cps 


cycles per second 


% 

o 

6 


number 




CRT 


cathode-ray tube 


ns 


nanosecond 




csk 


countersunk 


OD 


outside diameter 





A 


increment 


OHB 


oval head brass 




dB 


decibel 


OHS 


oval head steel 




dBm 


decibel referred to one milliwatt 


S2 


omega — ohms 




DC or dc 


direct current 


to 


omega — angular frequency 




DE 


double end 


P 


pico or 10" 12 





0 


degrees 


/ 


per 




°C 


degrees Celsius (degrees centigrade) 


% 


percent 




°F 


degrees Fahrenheit 


PHB 


pan head brass 




°K 


degrees Kelvin 


<i> 


phi — phase angle 




dia 


diameter 


rr 


pi— 3.1416 





-7- 


divide by 


PHS 


pan head steel 




div 


division 


+ 


plus 




EHF 


extremely high frequency 


± 


plus or minus 




elect. 


electrolytic 


PIV 


peak inverse voltage 




EMC 


electrolytic, metal cased 


piste 


plastic 





EMI 


electromagnetic interference (see RFI) 


PMC 


paper, metal cased 




EMT 


electrolytic, metal tubular 


poly 


polystyrene 




e 


epsilon — 2.71828 or % of error 


prec 


precision 




> 


equal to or greater than 


PT 


paper, tubular 




< 


equal to or less than 


PTM 


paper or plastic, tubular, molded 


. 


ext 


external 


pwr 


power 




F or f 


farad 


Q 


figure of merit 




F & 1 


focus and intensity 


RC 


resistance capacitance 




FHB 


flat head brass 


RF 


radio frequency 




FHS 


flat head steel 


RFI 


radio frequency interference (see E/ 


, 


Fil HB 


fillister head brass 


RHB 


round head brass 




Fil HS 


fillister head steel 


P 


rho — resistivity 




FM 


frequency modulation 


RHS 


round head steel 




ft 


feet or foot 


r/ min or rpm 


revolutions per minute 




G 


giga or 10 9 


RMS 


root mean square 


, — 


g 


acceleration due to gravity 


s or sec. 


second 




Ge 


germanium 


SE 


single end 




GHz 


gigahertz 


Si 


silicon 




GMV 


guaranteed minimum value 


SN or S/N 


serial number 




GR 


General Radio 


« 


small compared with 


, 


> 


greater than 


T 


tera or 10 12 




H or h 


henry 


TC 


temperature compensated 




h 


height or high 


TD 


tunnel diode 




hex. 


hexagonal 


THB 


truss head brass 




HF 


high frequency 


e 


theta — angular phase displacement 





HHB 


hex head brass 


thk 


thick 




HHS 


hex head steel 


THS 


truss head steel 




HSB 


hex socket brass 


tub. 


tubular 




HSS 


hex socket steel 


UHF 


ultra high frequency 




HV 


high voltage 


V 


volt 





Hz 


hertz (cycles per second) 


VAC 


volts, alternating current 




ID 


inside diameter 


var 


variable 




IF 


intermediate frequency 


VDC 


volts, direct current 




in. 


inch or inches 


VHF 


very high frequency 




incd 


incandescent 


VSWR 


voltage standing wave ratio 




00 


infinity 


W 


watt 




inf 


internal 


w 


wide or width 




7 


integral 


W/ 


with 




k 


kilohms or kilo ( 1 0 3 ) 


w/o 


without 




kfi 


kilohm 


WW 


wire-wound 





kc 


kilocycle 


xmfr 


transformer 




kHz 


kilohertz 








PARTS ORDERING INFORMATION 



Replacement parts are available from or through your local Tektronix, Inc. Field 
Office or representative. 

Changes to Tektronix instruments are sometimes made to accommodate improved 
components as they become available, and to give you the benefit of the latest circuit 
improvements developed in our engineering department. It is therefore important, when 
ordering parts, to include the following information in your order: Part number, instrument 
type or number, serial or mode! number, and modification number if applicable. 

If a part you have ordered has been replaced with a new or improved part, your 
local Tektronix, Inc. Field Office or representative will contact you concerning any change 
in part number. 



SPECIAL NOTES AND SYMBOLS 



xooo 

00 X 

* 000 - 0000-00 
Use 000-0000-00 

o 

rz 



Part first added at this serial number 
Part removed after this serial number 

Asterisk preceding Tektronix Part Number indicates manufactured by 
or for Tektronix, Inc., or reworked or checked components. 

Part number indicated is direct replacement. 

Screwdriver adjustment. 

Control, adjustment or connector. 




SECTION 7 



Type 191 



ELECTRICAL PARTS LIST 



Values are fixed unless marked Variable. 

Tektronix 

Ckt, No. Part No. Description S/N Range 



Bulb 

B1 09 150-0052-00 Incandescent, 10 V, 40 mA Pilot Light 



Capacitors 



Tolerance it20% unless otherwise indicated. 



C8 


281-0623-00 


650 pF 


Cer 




500 V 


5% 




C10A,B,C,D 


Use 281-0054-01 


4x15-1 50 pF 


Air 


Var 








C11 


285-0552-00 


0.018 juF 


PTM 




600 V 






Cl 2 


285-0591-00 


0.0047 fx F 


PTM 




600 V 


5% 




Cl 3 


283-0024-00 


0.1 ix F 


Cer 




30 V 






Cl 4 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








Cl 5 


285-0699-00 


0.0047 ix F 


PTM 




100V 


10% 




Cl 8 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








Cl 9 


283-0028-00 


0.0022 ix F 


Cer 




50 V 






C22 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








C23 


283-0078-00 


0.001 fxF 


Cer 




500 V 






C26 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








C27 


281-0551-00 


390 pF 


Cer 




500 V 


10% 




C30 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








C31 


281-0524-00 


150 pF 


Cer 




500 V 






C34 


281-0027-00 


0.7-3 pF 


Tub. 


Var 








C35 


281-0549-00 


68 pF 


Cer 




500 V 


10% 




C38 


281-0101-00 


1 .5-9.1 pF 


Air 


Var 






100-1019 


C38 


281-0102-00 


1.7-11 pF 


Air 


Var 






1020-up 


C39 


281-0504-00 


10 pF 


Cer 




500 V 


10% 




C60 


283-0025-00 


0.005 juF 


Cer 




500 V 


5% 




C61 


283-0026-00 


0.2 fx F 


Cer 




25 V 






C63 


283-0026-00 


0.2 fx F 


Cer 




25 V 






C64 


283-0025-00 


0.005 ,uF 


Cer 




500 V 


5% 




C66 


283-0026-00 


0.2 fx F 


Cer 




25 V 






C 67 


283-0025-00 


0.005 /*F 


Cer 




500 V 


5% 




C71 


283-0081-00 


0.1 fxF 


Cer 




25 V 


+80% -20% 




C72 


283-0078-00 


0.001 fx F 


Cer 




500 V 






C97 


283-0002-00 


0.01 ix F 


Cer 




500 V 




100-744 


C97 


283-0000-00 


0.001 


Cer 




500 V 




745-up 


Cl 01 


283-0078-00 


0.001 (x F 


Cer 




500 V 






Cl 02 


283-0078-00 


0.001 (x F 


Cer 




500 V 










7-1 




Electrical Parts List — Type 191 



Capacitors (Confc/J 



Tektronix 



Ckt. No. 


Part No. 




Description 




S/N Range 


Cl 09 


283-0051-00 


0.0033 /xF 


Cer 


100V 


5% 


Cl 13 


290-0278-00 


550 


EMC 


50 V 




Cl 1 5 


290-0278-00 


550 juF 


EMC 


50 V 




Cl 21 


283-0002-00 


0.01 ix F 


Cer 


500 V 




025 


283-0002-00 


0.01 juF 


Cer 


500 V 




027 


290-0171-00 


100 fx F 


EMT 


12 V 




028 


290-0209-00 


50 fx F 


EMT 


25 V 


+75%— 10% 


032 A,B 


290-0262-00 


2 x 40 juF 


EMC 


500 V 





Diodes 



D60 


*1 52-0205-00 


GaAs 


Glass diffused 


D67 


*1 52-0205-00 


GaAs 


Glass diffused 


D80 


*152-0185-00 


Silicon 


Replaceable by 1N3605 


D81 


*152-0185-00 


Silicon 


Replaceable by 1N3605 


D94 


*152-0185-00 


Silicon 


Replaceable by 1N3605 


D98 


152-0067-00 


Zener 


1M25Z10 1 W, 25 V, 10% 


Dll 2 A,B 
C,D (4) 


*152-0107-00 


Silicon 


Replaceable by 1N647 


D117 


152-0166-00 


Zener 


1N753A 0.4 W, 6.2 V, 5% 


D118 


*152-0107-00 


Silicon 


Replaceable by 1N647 


D132 A,B 


152-0208-00 


Silicon 


1N3195 



C,D (4) 



Fuses 



FI 01 159-0031-00 0.4 A, 3A G, Slo-Blo, 115 V 

FI 01 159-0044-00 0.2 A, 3AG, SIo-Blo, 230 V 



Connector 



J64 



131-0391-00 Coaxial, 50 n male 



Inductors 



Lll 


276-0507-00 


Core, Ferramic Suppressor 


LI 2 


276-0507-00 


Core, Ferramic Suppressor 


LI 3 


*108-0109-00 


60 fx H 


LI 5 


*108-0129-00 


18 fxH 


LI 9 


*108-0146-00 


5fxH 




Electrical Parts List — Type 191 



Inductors fConf’dJ 



Tektronix 

Ckt. No. Part No. 



Description 



S/N Range 



L23 


*108-0103-00 


2.5 ix H 


L27 


*108-0056-00 


1.2 juH 


L31 


*108-0262-00 


0.6 ixH 


L35 


*108-0260-00 


0.1 ix H 


L39 


*108-0262-00 


0.6 pH 


L49 


276-0525-00 


Core, Ferrite 


L61 


276-0528-00 


Core, Ferramic Suppressor 


L63 


276-0528-00 


Core, Ferramic Suppressor 


L64 


276-0525-00 


Core, Ferrite 


166 


276-0528-00 


Core, Ferramic Suppressor 


L 70 


276-0525-00 


Core, Ferrite 


L98 


*108-0008-00 


6.3 mH 



Plug 

PI 01 *131-0102-00 3 wire, male 



Transistors 



Q74 


*151-0155-00 


Silicon 


Replaceable by 2N2925 


Q84 


*151 -0155-00 


Silicon 


Replaceable by 2N2925 


Q93 


*151-0153-00 


Silicon 


Replaceable by 2N2923 


Q94 


151-0150-00 


Silicon 


2N3440 


Q123 


*151-0153-00 


Silicon 


Replaceable by 2N2923 


Q127 


Use *151-0087-00 


Silicon 


Replaceable by 2N1131 



Resistors 



Resistors are fixed, composition, zbl0% unless otherwise indicated. 



R8 


302-0563-00 


56 k O 


%W 






R13 


301-0750-00 


75 0 


Vi w 




5% 


R15 


301-0101-00 


100 0 


y 2 w 




5% 


R19 


301-0121-00 


1200 


Vi w 




5% 


R23 


301-0151-00 


1500 


Vi w 




5% 


R27 


301-0181-00 


180 0 


%w 




5% 


R31 


301-0221-00 


220 0 


y*w 




5% 


R35 


301-0271-00 


270 0 


%w 


- 


5% 


R39 


315-0270-00 


27 0 


Vi w 




5% 


R40 


323-0637-00 


50 0 


%W 


Prec 


v.% 


R41 


318-0092-00 


40.9 0 


'/.W 


Prec 


%% 


R42A 


318-0093-00 


20.2 0 


y.w 


Prec 


Vi% 


R42B 


318-0093-00 


20.2 0 


Vs W 


Prec 


Vi% 



7-3 




Electrical Parts List — Type 191 



Ckt. No. 



R43 

R44 

R45A 

R45B 

R46 



R47 

R48A 

R48B 

R49 

R51 



R52 

R53A 

R53B 

R53C 

R53D 



R53E 

R53F 

R53G 

R53H 

R53J 



R53K 

R53L 

R55 

R56 

R58 1 



R60 

R64 

R67 

R70 

R71 



R72 
R75 
R 76 
R80 
R81 



R83 

R84 

R90 

R92 

R93 



R94 

R95 

R96 

R97 



Resistors (ConfcfJ 



Tektronix 



Part No. 




Description 






318-0092-00 


40.9 a 


y.w 


Prec 


'/ 2 % 


318-0092-00 


40.9 a 


Vs W 


Prec 


v»% 


318-0093-00 


20.2 a 


y.w 


Prec 


Vi % 


318-0093-00 


20.2 0 


y.w 


Prec 


v»% 


318-0092-00 


40.9 0 


y.w 


Prec 


Vi% 


318-0092-00 


40.9 0 


y.w 


Prec 


'/ 2 % 


318-0093-00 


20.2 0 


Vs w 


Prec 


Vi% 


318-0093-00 


20.2 0 


y 8 w 


Prec 


y*% 


318-0092-00 


40.9 0 


y«w 


Prec 


v 2 % 


311-0344-00 


1000 


Var 







321-0129-00 


215a 


y.w 




Prec 


i% 


322-0649-00 


266 a 


'AW 




Prec 


y 2 % 


322-0649-00 


266 a 


’AW 




Prec 


y*% 


322-0649-00 


266 a 


’AW 




Prec 


Va% 


322-0649-00 


266 a 


’AW 




Prec 


Va% 


322-0649-00 


266 a 


’AW 




Prec 


Vi % 


322-0649-00 


266 a 


’AW 




Prec 


Va% 


322-0649-00 


266 a 


’AW 




Prec 


Vi % 


322-0649-00 


266 a 


’AW 




Prec 


%% 


322-0649-00 


266 a 


’AW 




Prec 


'/ 2 % 


322-0649-00 


266 a 


’AW 




Prec 


%% 


322-0649-00 


266 a 


’AW 




Prec 


'/ 2 % 


311-0404-00 


1 ka 




Var 






321-0174-00 


634 a 


y.w 




Prec 


1% 


*311-0586-00 


l ka 




Var 






316-0101-00 


ioo a 


’AW 








317-0220-00 


22 a 


1/10W 






5% 


316-0101-00 


ioo a 


’AW 








316-0101-00 


ioo a 


’AW 








302-0125-00 


1.2 Ma 


'AW 








316-0102-00 


l ka 


’AW 








315-0203-00 


20 ka 


'AW 






5% 


315-0681-00 


680 0 


'AW 






5% 


315-0821-00 


820 a 


’AW 






5% 


315-0103-00 


io ka 


’AW 






5% 


315-0203-00 


20 ka 


'AW 






5% 


315-0123-00 


12 ka 


’AW 






5% 


306-0102-00 


i ka 


2 W 








316-0272-00 


2.7 ka 


2 W 








315-0203-00 


20 ka 


'AW 






5% 


304-0474-00 


470 ka 


1 w 








302-0270-00 


27 a 


y 2 w 








302-0270-00 


27 a 


%w 








302-0474-00 


470 ka 


Vi w 









S/N Range 



1 Furnished as a unit with SW53. 




Electrical Parts List — Type 191 



Resistors (ConfcfJ 



Tektronix 



Ckt. No. 


Part No. 




Description 






S/N Range 


R98 


306-0102-00 


1 kn 


2 W 








R99 


306-0102-00 


i kn 


2 W 








R109 


302-0151-00 


150 n 


’AW 








Rill 


316-0100-00 


ion 


’AW 








R112 


316-0100-00 


ion 


’AW 








R115 


315-0680-00 


68 Q 


’AW 




5% 


100-1059 


R115 


315-0820-00 


82 n 


’AW 




5% 


1060-1353 


R1 1 5 


315-0910-00 


91 n 


’AW 


Selected (nominal value) 




1354-up 


R117 


301-0432-00 


4.3 kn 


’AW 








R1 1 8 


303-0272-00 


2.7 kn 


1 w 




5% 




R120 


321-0239-00 


3.01 kn 


’AW 


Prec 


1% 




R121 


321-0258-00 


4.75 kn 


’AW 


Prec 


1% 




R122 


311-0404-00 


i kn 




Var 






R123 


323-0222-00 


2kn 


’AW 


Prec 


1% 




R125 


316-0223-00 


22 kn 


’AW 








R131 


302-0100-00 


ion 


’AW 








R132 


304-0271-00 


270 n 


1 w 








R135 


306-0184-00 


180kn 


2 W 








R137 


302-0394-00 


390 kn 


’AW 








R138 


302-0274-00 


270 kn 


’AW 








R140 


304-0472-00 


4.7 kn 


1 w 













Switches 






Unwired Wired 






SW10 


260-0768-00 *262-0744-00 


Rotary 


FREQUENCY RANGE 


SW40 


260-0769-00 *262-0743-00 


Rotary 


AMPLITUDE RANGE 


SW53 2 


260-0770-00 *262-0745-00 


Rotary 


AMPLITUDE 


SW101 


260-0014-00 


Toggle 


POWER 


SW105 


260-0675-00 


Slide 


1 1 5 V - 230 V 









Transformers 






T10 


*114-0204-00 


2.3-4 mH 


Var 


core 


276-0508-00 


T14 


*114-0203-00 


1 .5-2.5 mH 


Var 


core 


276-0508-00 


T18 


*114-0060-00 


0.4-7.6 mH 


Var 


core 


276-0508-00 


T22 


*114-0061-00 


70-99 fi \ H 


Var 


core 


276-0508-00 


T26 


*114-0062-00 


9-1 6 pH 


Var 


core 


276-0508-00 


T30 


*114-0063-00 


1 .8-3 fiH 


Var 


core 


276-0508-00 


T34 


*114-0202-00 


0.28-0.4 ixH 


Var 


core 


276-0508-00 


T38 


Use *114-0201-01 


80-100 nH 


Var 


core 


276-0506-00 


T101 


*120-0424-00 


LV Power 









V10 


154-0340-00 


7119 


Electron Tubes 


V94 


154-0340-00 


7119 




2 Furnished as a 


unit with R58. 







7-5 




FIGURE AND INDEX NUMBERS 



Items in this section are referenced by figure and index numbers to the illustrations 
which appear on the pullout pages immediately following the Diagrams section of this 
instruction manual. 



INDENTATION SYSTEM 

This mechanical parts list is indented to indicate item relationships. Following is an 
example of the indentation system used in the Description column. 

Assembly and/or Component 

Detail Part of Assembly and/or Component 
mounting hardware for Detail Part 
Parts of Detail Part 

mounting hardware for Parts of Detail Part 
mounting hardware for Assembly and/or Component 

Mounting hardware always appears in the same indentation as the item it mounts, 
while the detail parts are indented to the right. Indented items are part of, and included 
with, the next higher indentation. 

Mounting hardware must be purchased separately, unless otherwise specified. 



PARTS ORDERING INFORMATION 

Replacement parts are available from or through your local Tektronix, Inc. Field Office 
or representative. 

Changes to Tektronix instruments are sometimes made to accommodate improved 
components as they become available, and to give you the benefit of the latest circuit 
improvements developed in our engineering department. It is therefore important, when 
ordering parts, to include the following information in your order: Part number, instru- 
ment type or number, serial or model number, and modification number if applicable. 

If a part you have ordered has been replaced with a new or improved part, your 
local Tektronix, Inc. Field Office or representative will contact you concerning any change 
in part number. 

Change information, if any, is located at the rear of this manual. 



ABBREVIATIONS AND SYMBOLS 



For an explanation of the abbreviations and symbols used in this section, please refer 
to the page immediately preceding the Electrical Parts List in this instruction manual. 




Mechanical Parts List — Type 191 



INDEX OF MECHANICAL PARTS LIST ILLUSTRATIONS 



FIG. 


1 


FRONT 


FIG. 


2 


CHASSIS 


FIG. 


3 


CABINET 


FIG. 


4 


ACCESSORIES 



TYPE 191 CONSTANT AMPLITUDE SIGNAL GENERATOR 




SECTION 8 



Type 191 



Fig. & 
Index 
No. 



1-1 

-2 

-3 



-4 

-5 



-6 



-7 

-8 



-9 



-10 

-11 

-12 



-13 



-14 



-15 



-16 

-17 



MECHANICAL PARTS LIST 

FIG. 1 FRONT AND REAR 



Q 

Tektronix Serial/Model No. t 

Part No. Eff Disc y 



333-0927-00 






1 


386-1019-00 






1 


366-0117-01 






1 


213-0004-00 






1 


331-0170-00 






1 


211-0099-00 






3 


331-0140-00 






1 


213-0020-00 






2 


354-0289-00 






1 


210-0586-00 






4 








1 


344-0136-00 


X264 




1 


407-0222-00 






1 


407-0221-00 






1 


212-0001-00 


100 


369 


4 


212-0084-00 


370 




4 


210-0804-00 


X370 




4 


211-0507-00 






4 


210-0803-00 






4 


366-0322-01 






1 


213-0004-00 






1 


262-0744-00 






1 


260-0768-00 






1 


131-0375-00 






1 


210-0413-00 






1 


210-0840-00 






1 


210-0012-00 






1 



Description 

1 2 3 4 5 



PANEL; front 
PLATE; sub-panel 
KNOB, charcoal — Frequency Dial 
knob includes: 

SCREW, set, 6-32 x 3 /i6 inch, HSS 
POINTER 

mounting hardware: (not included with pointer) 
SCREW, 4-40 x 5 /u inch, 100° csk, FHS 

DRIVE, dial, 3:1 ratio 
drive includes: 

SCREW, set, 6-32 x % inch, HSS 
mounting hardware: (not included with drive) 
RING, mounting 
NUT, keps, 4-40 x% inch 



CAPACITOR, variable 
capacitor includes: 

CLIP, ground 

mounting hardware: (not included with capacitor) 

BRACKET, angle, rear 

BRACKET, angle, front 

SCREW, 8-32 x y 4 inch, PHS 

SCREW, 8-32 x 5 / u inch, HHS 

WASHER, flat, 0.170 IDx 3 / 8 inch OD 

SCREW, 6-32 x 5 /u inch, PHS 

WASHER, flat, 0.150 ID x % inch OD 



KNOB, charcoal— FREQUENCY RANGE 
knob includes: 

SCREW, set, 6-32 x Vu inch, HSS 
SWITCH, wired— FREQUENCY RANGE 
switch includes: 

SWITCH, unwired 
CONNECTOR, coaxial, 1 -contact 
mounting hardware: (not included with switch) 
NUT, hex., Vs-32 x y 2 inch 
WASHER, flat, 0.390 ID x 9 / u inch OD 
LOCKW ASHER, internal, % ID X y 2 inch OD 



8-1 




Mechanical Parts List — Type 191 



Fig. & 
Index 
No. 

1-18 

-19 

-20 

-21 

-22 

-23 

-24 

-25 

-26 

-27 

-28 

-29 

-30 

-31 

-32 

-33 

-34 

-35 

-36 



FIG. 1 FRONT AND REAR (Cont) 



Q 



Tektronix 


Serial/Model 


No. 


t 


Part No. 


Eff 


Disc 


y 


260-0014-00 






l 


210-0414-00 






1 


354-0055-00 






i 


210-0902-00 






l 


210-0473-00 






i 



670-0224-00 






1 


388-0681-00 






1 


214-0506-00 






3 


131 0391-00 






1 


352-0041-00 






3 


220-0449-00 


100 


259 


2 


211-0116-00 


100 


259 


2 


210-0994-00 


260 




2 


210-0004-00 


260 




2 


210-0406-00 


260 




2 



366-0189-00 


1 


213-0020-00 


1 


366-0322-00 


1 


213-0004-00 


1 


262-0745-00 


1 


260-0770-00 


1 


166-0026-00 


2 


211-0016-00 


2 


210-0054-00 


2 

1 


213-0022-00 


2 


384-0358-01 


1 


210-0413-00 


1 


210-0840-00 


1 


210-0012-00 


1 


136-0164-00 


1 


210-0413-00 


1 


210-0012-00 


1 


210-0978-00 


1 


210-0590-00 


1 



Description 

1 2 3 4 5 



SWITCH, toggle— POWER 

mounting hardware: (not included with switch) 

NUT, hex., 15 / 32 -32 x 9 / 16 inch 

RING, locking, switch 

WASHER, flat, 0.470 IDx 21 / 32 inch OD 

NUT, switch, 15 / 32 -32 x 0.634 inch, 12 sided 



ASSEMBLY, circuit board— DETECTOR 
assembly includes: 

BOARD, circuit 
board includes: 

PIN, connector, straight 
CONNECTOR, coaxial, 1 -contact 
CLIP, diode 

mounting hardware: (not included with assembly) 
NUT, hex., 4-40 x y 4 x ] / 2 inch long 
SCREW, sems, 4-40 x 5 / u inch, PHB 
WASHER, flat, 0.125 ID x 0.250 inch OD 
LOCKWASHER, internal, #4 
NUT, hex., 4-40 x 3 / u inch 



KNOB, red— VARIABLE 
knob includes: 

SCREW, set, 6-32 x % inch, HSS 
KNOB, charcoal— AMPLITUDE 
knob includes: 

SCREW, set, 6-32 x 3 / 14 inch, HSS 
SWITCH, wired— AMPLITUDE 
switch includes: 

SWITCH, unwired 

TUBE, spacer, 0.125 IDx 3 /i«$ OD x 3 / 8 inch long 
SCREW, 4-40 x % inch, RHS 
LOCKWASHER, split, #4 
RESISTOR, variable 
resistor includes: 

SCREW, set, 4-40x 3 / 16 inch, HSS 
ROD, extension 

mounting hardware: (not included with switch) 
NUT, hex., 3 / 8 -32xy 2 inch 
WASHER, flat, 0.390 ID x 9 /u inch OD 
LOCKWASHER, internal, % ID x y 2 inch OD 



SOCKET, lamp 

mounting hardware: (not included with socket) 
NUT, hex., 3 /s-32 x y 2 inch 
LOCKWASHER, internal, 13 / s ID x y 2 inch OD 
WASHER, flat, 3 / 8 ID x y 2 inch OD 
NUT, hex., y 8 -32 x 7 / u inch 



8-2 



© 




Mechanical Parts Ust — Type 191 



FIG. 1 FRONT AND REAR (ContJ 



Fig. & 
index 
No. 


Tektronix 
Part No. 


Serial/Model No. 
Eff Disc 


Q 

t 

y 


Description 

1 2 3 4 5 


1-37 


366-0322-01 




l 


KNOB, charcoal— AMPLITUDE RANGE 








. 


knob includes: 




213-0004-00 




l 


SCREW, set, 6-32 x 3 / u inch, HSS 


-38 


262-0743-00 




i 


SWITCH, wired— AMPLITUDE RANGE 








- 


switch includes: 




260-0769-00 




l 


SWITCH, unwired 


-39 


132-0121-00 




1 


NUT, retaining 


-40 


175-0376-00 




l 


ASSEMBLY, cable and connector 








- 


assembly includes: 


-41 


166-0221-00 




2 


TUBE, ferrule 


-42 


132-0002-00 




1 


SLEEVE, conductor, outer 


-43 


132-0029-00 




1 


CONDUCTOR, inner 


-44 


132-0028-00 




1 


INSULATOR 


-45 


132-0116-00 




1 


TRANSITION, inner 


-46 


132-0007-00 




1 


RING, snap 


-47 


132-0115-00 




1 


TRANSITION, outer 




132-0119-00 




1 


DISC, plastic (not shown) 


-48 


166-0239-00 




1 


TUBE, adapter, coaxial 


-49 


132-0001-00 




1 


NUT, coupling 








- 


mounting hardware: (not included with switch) 


-50 


210-0413-00 




1 


NUT, hex., %-32 x Vi inch 


-51 


210-0840-00 




1 


WASHER, flat, 0.390 IDx’/u inch OD 


-52 


132-0040-00 




1 


ADAPTER, panel 








- 


mounting hardware; (not included with adapter) 


-53 


211-0101-00 




4 


SCREW, 4-40 xV 4 inch, 100° csk, FHS 


-54 


131-0102-00 




1 


ASSEMBLY, 3 wire connector 








- 


assembly includes: 


-55 


129-0041-00 




1 


POST, ground 


-56 


200-0185-00 




1 


COVER, plastic 


-57 


211-0015-00 




1 


SCREW, 4-40 x y 2 inch, RHS 


-58 


214-0078-00 




2 


PIN, connecting 


-59 


377-0041-00 




1 


INSERT, plastic 


-60 


386-0933-00 




1 


PLATE 


-61 


210-0406-00 




2 


NUT, hex., 4-40 x 3 / 16 inch 




210-0003-00 




2 


LOCKWASHER, external, #4 








- 


mounting hardware: (not included with assembly) 




211-0542-00 




2 


SCREW, 6-32 x 5 / ]6 inch, THS 


-62 


210-0457-00 




2 


NUT, keps, 6-32 x 5 /^ inch 




210-0202-00 




2 


LUG, solder, SE #6 


-63 


352-0002-00 




1 


ASSEMBLY, fuse holder 








- 


assembly includes: 


-64 


352-0010-00 




1 


HOLDER, fuse 


-65 


210-0873-00 




1 


WASHER, rubber, y 2 ID x u /u inch OD 


-66 


200-0582-00 




1 


CAP, fuse 


-67 






1 


NUT, hex. 



© 



8-3 




Mechanical Parts List — Type 191 



FIG. 1 FRONT AND REAR (Cont) 



Fig. & Q 

Index Tektronix Serial/Model No. t 

No. Part No. Eff Disc y 12345 



Description 



1-68 


214-0680-00 




1 




210-0458-00 




1 


-69 


386-1018-00 




1 


-70 


384-0615-00 




3 


-71 


212-0044-00 




1 


-72 


351-0096-00 




1 




212-0044-00 




1 




211-0559-00 




2 


-73 


214-0680-00 




1 


-74 


214-0553-00 




1 


-75 


358-0255-00 




1 


-76 


213-0120-00 


100 


219 2 




211-0001-00 


220 


2 




210-0405-00 


X220 


2 


-77 


260-0675-00 




1 


-78 


211-0008-00 




2 




210-0406-00 




2 



PIN, locating 

mounting hardware: (not included with pin) 
NUT, keps, 8-32 x 1 1/32 inch 



PLATE, rear 
ROD, spacer 

mounting hardware for each: (not included with rod) 
SCREW, 8-32 x y 2 inch, RHS 



GUIDE, rail 

mounting hardware: (not included with guide) 
SCREW, 8-32 X y 2 inch, RHS 
SCREW, 6-32 x 3 / s inch, 100° csk, FHS 
PIN, locating 



SCREW, latch 
BUSHING, latch 

SCREW, thread forming, 2-32 x y 4 inch, PHS 
SCREW, 2-56 x y 4 inch, RHS 
NUT, hex., 2-56 x 3 /i* inch 



SWITCH, slide — 1 1 5 V-230 V 
mounting hardware: (not included with switch) 
SCREW, 4-40 xV 4 inch, PHS 
NUT, hex., 4-40 x 3 /u inch 



8-4 




Mechanical Parts List — Type 191 



FIG. 2 CHASSIS 



— 


Fig. & 
Index 
No. 


Tektronix 
Part No. 


Serial/Model No. 
Eff Disc 


Q 

t 

y 


Description 

1 2 3 4 5 




2-1 


441-0663-00 




l 


CHASSIS, vertical 


— 








- 


mounting hardware: (not included with chassis) 






211-0542-00 




2 


SCREW, 6-32 x 5 / u inch, THS 






211-0538-00 




3 


SCREW, 6-32 x 5 / u inch, 100° csk, FHS 




-2 


441-0662-00 




1 


CHASSIS, power 










- 


mounting hardware: (not included with chassis) 






211-0507-00 




1 


SCREW, 6-32 x 5 /u inch, PHS 


— 




211-0542-00 




2 


SCREW, 6-32 x 5 /,, s inch, THS 




-3 


136-0181-00 




6 


SOCKET; transistor, 3-pin 




-4 


354-0234-00 




6 


RING, socket mounting 




-5 


210-0201-00 




12 


LUG, solder, SE #4 










- 


mounting hardware for each: (not included with lug) 




-6 


213-0044-00 




1 


SCREW, thread forming, 5-32x 3 / 16 inch, PHS 




-7 


426-0121-00 




1 


HOLDER, toroid 




-8 


361-0007-00 




1 


SPACER, plastic, 0.188 inch long 




-9 






1 


RESISTOR, variable 










- 


mounting hardware: (not included with resistor) 






210-0583-00 




1 


NUT, hex., V 4 -32 x s / u inch 






210-0940-00 




1 


WASHER, flat, ’/ 4 ID x % inch OD 




-10 






1 


CAPACITOR 










- 


mounting hardware*, (not included with capacitor) 




-n 


386-0253-00 




1 


PLATE, metal, small 


— 




211-0534-00 




2 


SCREW, sems, 6-32 x s /i 6 inch, PHS 






210-0457-00 




2 


NUT, keps, 6-32 x 5 / 16 inch 




-12 


358-0215-00 




1 


BUSHING, plastic 




-13 






7 


COIL 










- 


mounting hardware for each: (not included with coil) 




-14 


210-0413-00 




1 


NUT, hex., 3 / 8 -32 xV 2 inch 


.... 


-15 


210-0840-00 




1 


WASHER, flat, 0.390 ID x 9 / ]6 inch OD 




-16 


210-0407-00 




1 


NUT, hex., 6-32 x 7 / 4 inch 






210-0012-00 




1 


LOCKW ASHER, internal, % ID x y 2 inch OD 


— 


-17 






1 


COIL 










- 


mounting hardware: (not included with coil) 




-18 


211-0507-00 




1 


SCREW, 6-32x 5 /i 6 inch, PHS 




-19 






2 


RESISTOR, variable 










- 


mounting hardware for each: (not included with resistor) 




-20 


210-0583-00 




1 


NUT, hex., y 4 -32x 5 / 16 inch 






210-0940-00 




1 


WASHER, flat, y 4 ID x 3 / 8 inch OD 




-21 


214-0210-00 




1 


ASSEMBLY, solder spool 


— 








- 


assembly includes: 






214-0209-00 




1 


SPOOL, w/o solder 










- 


mounting hardware: (not included w/assembly) 






361-0007-00 




1 


SPACER, plastic, 0.188 inch long 




-22 


343-0088-00 




2 


CLAMP, cable, small 



8-5 




Mechanical Parts List — Type 191 



FIG. 2 CHASSIS (Conf) 



Fig. & Q 

Index Tektronix Serial/Model No. t Descriotion 

No. Part No. Eff Disc y 12345 

2-23 348-0031-00 2 GROMMET, plastic, 5 / 32 inch diameter 

-24 348-0056-00 1 GROMMET, plastic, % inch diameter 

-25 348-0055-00 1 GROMMET, plastic, Vi inch diameter 

-26 1 TRANSFORMER 

- transformer includes: 

-27 212-0515-00 4 SCREW, 10-32x2Vi inch, HHS 

210- 0812-00 4 WASHER, fiber, 0.190 ID x 0.380 inch OD 

------ - mounting hardware: (not included with transformer) 

-28 220-0410-00 4 NUT, keps, 10-32x 3 / 8 inch 

-29 136-0074-00 1 SOCKET, tube, 9-pin, w/o saddle 

- mounting hardware: (not included with socket) 

-30 354-0109-00 1 HOLDER, tube socket 

-31 337-0005-00 1 SHIELD, tube socket 

211- 0012-00 2 SCREW, 4-40 x% inch, PHS 

210-0586-00 2 NUT, keps, 4-40 x Vi inch 

-32 337-0810-00 2 SHIELD, tube 

-33 1 CAPACITOR 

- mounting hardware: (not included with capacitor) 

-34 386-0252-00 1 PLATE, fiber, small 

-35 211-0534-00 2 SCREW, sems, 6-32x 5 / 16 inch, PHS 

210-0457-00 2 NUT, keps, 6-32x 5 / 16 inch 

-36 200-0256-00 1 COVER, capacitor 

-37 1 CAPACITOR 

- mounting hardware: (not included with capacitor) 

-38 386-0255-00 1 PLATE, metal, large 

-39 211-0534-00 2 SCREW, sems, 6-32 x 5 /i<s inch, PHS 

210-0457-00 2 NUT, keps, 6-32x 5 / 16 inch 

-40 1 CAPACITOR 

- - mounting hardware; (not included with capacitor) 

-41 214-0456-00 1 FASTENER, plastic 

-42 136-0022-00 1 SOCKET, tube, 9-pin, w/shield 

- mounting hardware: (not included with socket) 

213-0044-00 2 SCREW, thread forming, 5-32 x 3 /^ inch, PHS 

-43 179-1024-00 1 CABLE HARNESS 

- cable harness includes: 

131-0371-00 3 CONNECTOR, single contact 

-44 124-0149-00 1 STRIP, ceramic, 7 /u inch h, w/7 notches 

- strip includes: 

355-0046-00 2 STUD, plastic 

- mounting hardware: (not included with strip) 

361-0009-00 2 SPACER, plastic, 0.406 inch long 

-45 124-0162-00 2 STRIP, ceramic, 7 / u inch h, w/4 notches 

- each strip includes: 

355-0046-00 1 STUD, plastic 

- mounting hardware for each: (not included with strip) 

361-0009-00 1 SPACER, plastic, 0.406 inch long 



8-6 




Mechanical Parts List — Type 191 



FIG. 2 CHASSIS (ConfJ 



Fig. & Q 

Index Tektronix Serial/Model No. t Description 

No. Part No. Eff Disc y 12345 



246 124-0146-00 

355-0046-00 
361-0009-00 



2 STRIP, ceramic, 7 / u inch h, w/16 notches 
each strip includes: 

2 STUD, plastic 

mounting hardware for each: (not included with strip) 
2 SPACER, plastic, 0.406 inch long 



47 124-0149-00 

355-0046-00 
361-0009-00 



1 STRIP, ceramic, 7 /y> inch h, w/7 notches 

strip includes: 

2 STUD, plastic 

mounting hardware: (not included with strip) 
2 SPACER, plastic, 0406 inch long 



48 124-0145-00 

355-0046-00 
361-0009-00 



2 STRIP, ceramic, 7 / u inch h, w/20 notches 
each strip includes: 

2 STUD, plastic 

mounting hardware for each: (not included with strip) 
2 SPACER, plastic, 0.406 inch long 



8-7 




Mechanical Parts List — Type 191 



FIG. 3 CABINET 



Fig. & 

Index Tektronix Serial/Model No. 

No. Part No. Eff Disc 



Q 

t 

Y 1 2 3 4 S 



Description 



437-0078-00 1 

3-1 386-0141-00 2 

212 - 0002-00 2 

-2 426-0253-00 1 

-3 377-0121-00 1 

-4 426-0252-00 1 

-5 377-0120-00 1 

-6 426-0254-00 1 

212-0004-00 2 

212 - 0002-00 2 

-7 426-0255-00 1 

212-0002-00 4 

-8 351-0093-00 1 

212-0023-00 1 

210-0007-00 1 



-9 351-0092-00 

-10 358-0293-01 



211- 0510-00 
210-0005-00 

212 - 0001-00 
210-0007-00 



-11 358-0294-01 



211- 0510-00 
210-0005-00 

212 - 0001-00 
210-0007-00 



-12 386-0139-00 1 

-13 386-0140-00 1 

-14 386-0138-00 1 

-15 348-0075-00 2 



212-0004-00 2 



CABINET 
cabinet includes: 

PLATE, side 

mounting hardware for each: (not included w/plate alone) 
SCREW, 8-32 x’/ 4 inch, 100° csk, FHS 



FRAME, front, left 
INSERT, frame, left 
FRAME, front, right 
INSERT, frame, right 
FRAME, front, bottom 

mounting hardware: (not included w/frame alone) 
SCREW, 8-32 x s /u inch, PHS 
SCREW, 8-32 x 1 /, inch, 100° csk, FHS 



FRAME, front, top 

mounting hardware: (not included w/frame alone) 
SCREW, 8-32 x '/, inch, 100° csk, FHS 



GUIDE, left 

mounting hardware: (not included w/guide alone) 
SCREW, 8-32 x% inch, PHS 
LOCKWASHER, external, #8 



GUIDE, right 

BUSHING, plug-in securing, left 

mounting hardware: (not included w/bushing alone) 

SCREW, 6-32 x 3 /e inch, PHS 

LOCKWASHER, external, #6 

SCREW, 8-32 x inch, PHS 

LOCKWASHER, external, #8 

BUSHING, plug-in securing, right 

mounting hardware: (not included w/bushing alone) 

SCREW, 6-32 x% inch, PHS 

LOCKWASHER, external, #6 

SCREW, 8-32 x inch, PHS 

LOCKWASHER, external, #8 



PLATE, rear 
PLATE, bottom 
PLATE, top 

FOOT, rear guard, left and right 

mounting hardware for each: (not included w/foot alone) 
SCREW, 8-32 x 5 / 16 inch, PHS 



8-8 




Mechanical Parts List — Type 191 



FIG. 3 CABINET (Cont) 



Fig. & 
Index 
No. 


Tektronix 
Part No. 


Serial/Model No. 
Eff Disc 


Q 

t 

y 


Description 

1 2 3 4 5 


3-16 


348-0074-00 




1 


FOOT, rear, left 








- 


mounting hardware: (not included w/foot alone) 




211-0532-00 




2 


SCREW, 6-32 x % inch, Fil HS 




348-0074-00 




1 


FOOT, front, right 








- 


mounting hardware: (not included w/foot alone) 




211-0532-00 




2 


SCREW, 6-32 x % inch, Fil HS 




210-0457-00 




1 


NUT, keps, 6-32 x s /, 6 inch 


-17 


378-0073-00 




i 


FOOT, front, left 








- 


mounting hardware: (not included w/foot alone) 




211 0532-00 




2 


SCREW, 6-32 x s / 4 inch, Fil HS 




210-0457-00 




1 


NUT, keps, 6-32 x 5 / 16 inch 




348-0073-00 




1 


FOOT, rear, right 








- 


mounting hardware: (not included w/foot alone) 




211-0532-00 




2 


SCREW, 6-32 x 3 / 4 inch, Fil HS 


-18 


377-0119-00 




4 


INSERT, foot 


-19 


348-0072-00 




1 


FOOT, flip-stand bail 


-20 


367-0052-00 




1 


HANDLE 








- 


mounting hardware: not included w/handle alone) 




212-0040-00 




2 


SCREW, 8-32 x % inch, 100° csk, FHS 


-21 


367-0051-00 




1 


PIVOT, handle, left 


-22 


377-0123-00 




1 


PIVOT, insert, left 


-23 


367-0050-00 




1 


PIVOT, handle, right 


-24 


377-0122-00 




1 


PIVOT, insert, right 


-25 


214-0054-00 




2 


BOLT, hinge 




214-0558-00 




2 


WASHER, thrust, s /u^Vi inch 





type: i9i 



A 












sw^o 



A 



MRW 

1065 

BLOCK DIAGRAM 









IMPORTANT 

VOLTAGE AND WAVEFORM CONDITIONS 

Circuit voltages measured with a 20,000 12/volt VOM. All read- 
ings in volts. Voltages are measured with respect to chassis ground 
unless otherwise noted. 



Waveforms shown are actual waveform photographs taken with 
a Tektronix Oscilloscope Camera System and Projected Graticule. 



Voltages and waveform on the schematics (shown in blue) are not 
absolute and may vary between instruments. 

The test oscilloscope used had the following characteristics: Mini- 
mum deflection factor, 0.5 volts/division using a 10X probe; fre- 
quency response, dc to 30 MHz; AC input coupling was used. 

To indicate true time relationship between signals, the test oscillo- 
scope was externally triggered from the sampling point. 

Voltage readings and waveforms were obtained under the follow- 
ing conditions unless otherwise noted on the individual diagrams: 

POWER ON 



OUTPUT (Connector) 
AMPLITUDE RANGE 
AMPLITUDE 

VARIABLE (AMPLITUDE) 
FREQUENCY RANGE 



Terminated with 50 ohms 
.5-5 V 
50 
CAL 

50 kHz ONLY 



Frequency (dial) Set to .5 mark of . 35-75 scale 

115V/230V (rear panel) Set for correct line voltage 




FREQUENCY 










o o 



■ PARTS LIST FOR EARLIER 
LUES AND SERIAL NUMBER 
NGES OF PARTS MARKED 
TH BLUE OUTLINE. 



5<b7 

MRU 



CONSTANT AMPLITUDE SIGNAL GENERATOR 






+ 




FIG. 4 STANDARD ACCESSORIES 




TYPE 191 CONSTANT AMPLITUDE SIGNAL GENERATOR 



Fig. & 

Index Tektronix 
No. Part No. 



Serial/Model No. 
Eff Disc 



Q 

t 

y 1 2 3 4 5 



Description 



4-1 161-0024-00 100 1349 

161-0024-01 1350 

-2 103-0013-00 

-3 017-0502-00 

-4 017-0083-00 

070-0522-00 



1 CORD, power, 3-conductor, 8 feet 
1 CORD, power, 3-conductor, 8 feet 
1 ADAPTER, power cord, 3 to 2 wire 
1 CABLE, 50 ohm, 5 ns 

1 TERMINATION, 50 ohm, GR to BNC 

2 MANUAL, instruction (not shown) 




MANUAL CHANGE INFORMATION 



At Tektronix, we continually strive to keep up with 
latest electronic developments by adding circuit and 
component improvements to our instruments as soon 
as they are developed and tested. 

Sometimes, due to printing and shipping require- 
ments, we can’t get these changes immediately into 
printed manuals. Hence, your manual may contain new 
change information on following pages. If it does not, 
your manual is correct as printed. 




TYPE 191 



CORRECTION NOTICE 

Due to a temporary shortage of 40.9 1/8 W, resistors, a 41.2 Q, 1/8 W, 

1 % resistor, selected to be within the tolerance range of the original resistor, 
may have been substituted for R4l, R43, R44, R46, H47 and R49 in this instrument. 

When ordering replacement parts, order the 40.9 2 resistor for which infor- 
mation is given in the parts list. 



\ 



Mil, 663/1066 




TYPE 191 



TENT SN 1660 



PASTS LIST CORRECTION 



CHANGE TO: 

B109 I 5 O-OO 65 -OO Imca*d«*c«nt , 10 V, 40 mk 



M12, 031/667 




TYPE 191 



TENT SN 1580 



PARTS LIST CORRECTION 

CHANGE TO: 

Q94 151-0169-00 Silicom 2N3439 

ADD: 

R91 302-0474-00 470 K 1/2 W 10 % 

SCHEMATIC CORRECTION 



+450V 

UUREG 




PARTIAL 

CONSTANT AMPLITUDE SIGNAL GENERATOR 



\ 



M12, 151/667 




TYPE 191 



TENT SN 1354 



PARTS LIST CORRECTION 



CHANGE TO: 

R115 315-0910-00 91 0 (nominal installed value) 



1 A w 3 % 



M12, 422/567